THE LUMINOSITY FUNCTION OF LOW-MASS STARS AND
BROWN DWARFS
Kelle Lin Cruz
A DISSERTATION
in
Physics and Astronomy
Presented to the Faculties of the University of Pennsylvania
in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy
2004
Supervisor of Dissertation
Graduate Group Chairperson
Acknowledgements
There are many people who have influenced my path towards the pursuit of science and who
have made that experience not just possible, but more enjoyable. I am of course grateful for my
parents for their support of my academic endeavors and for passing on to me their traits of ambition,
self-confidence, and self-reliance. I am also very appreciative of my partner, Jeff Kaplan, and our
family, Dali, Molly, and Snuffles, for their loving support and for encouraging me to get out of the
office.
In addition, I would like to thank my Mom for making me realize that leaving Texas for college
was an actual possibility. Also to Bill McCumber, a Penn recruitment officer, who spent several
hours on the phone with my Dad before I left the peaceful Texas Hill Country for the mean streets
of Philadelphia. I am also extremely grateful for the the three-summer San Antonio PreFreshman
Engineering Program (PREP) for an early exposure to rigorous science and mathematics and for a
much-needed college preparatory experience.
As an eager undergraduate in the Penn Astro Group, I am fortunate to have had several
excellent mentors including Mark Devlin, Deborah Goldader, Jeff Klein, Dave Koerner, Steve Myers,
and Jason Puchalla. More recently, I have been privileged to collaborate with Jim Liebert, Davy
Kirkpatrick, and Adam Burgasser.
It is difficult to express how much I value the guidance of my thesis advisor, Neill Reid. I was
lucky to be in the right place at the right time to work with him as an undergraduate and then to
embark on this project under his supervision. I hope that we continue to collaborate for many years
to come.
I would not have completed, nor remained emotionally stable during my undergraduate and
graduate coursework without wonderful study buddies who include Peter Allen, Elizabeth Caffrey,
Paige Derr, Jonathon Fisher, Nitya Kallivayalil, Marie Rex, and Ariel Michelman Ribeiro. I am
especially indebted to Peter Allen for daily discussions about low-mass stars and brown dwarfs. My
understanding of the subject would not be nearly as thorough and broad without his patience and
camaraderie.
I am extremely thankful for all the WISPers who have provided never-ending friendship and
support: Federica Bianco, Nina Bonaventura, Anna Bracewell, Elizabeth Caffrey, Rachel Courtland,
ii
Monica Dunford, Marjia Drndic, Deborah Goldader, Marya Grzesiak, Faye Ip, Nitya Kallivayalil,
Yael Katz, Suliana Manley, Andrea Morton, Reiko Nakajima, Taryn Nihei, Angelica de OliveiraCosta, Sophie Pautot, Marie Rex, Ariel Michelman Riberio, Megan Schwamb, Megan Valentine, and
Dorothy Wang. And to Doug Cowen, for making it all possible.
I would also like to express my appreciation for my tennis buddies, past and present: Carolyn
Blackwell, Elinor Haider, Chuck Hammond, Mary Hubele, Gloria Graham, and Bhuvnesh Jain.
I would like to thank the various NOAO TACs for giving this program a significant amount
of telescope time. I am also indebted to the numerous telescope operators and support staff that
made this work possible and who endured my busy observing program. At KPNO: Ed Eastburn,
Bill Gillespie, John Glaspey, Hal Halbedel, Diane Harmer, Hillary Mathis, and Daryl Willmarth; at
CTIO: Alberto Alvarez, Edgardo Cosgrove, Arturo Gomez, Angel Guerra, Daniel Maturana, Sergio
Pizarro, and Patricio Ugarte.
I would also like to thank Adam and Albert Burgasser for providing the inspiration to use
Microsoft Access. Contrary to other’s experience with Microsoft products, this program has greatly
increased the ease with which I navigate through the thousands of nearby ultracool candidates
uncovered as part of the program described in this dissertation.
This work was financially supported by a NSF Graduate Research Fellowship and a grant from
the NASA/NSF NStars initiative, administered by JPL. This publication makes extensive use of
data products from the Two Micron All-Sky Survey, which is a joint project of the University of
Massachusetts and IPAC/CalTech, funded by NASA and the NSF; the NASA/IPAC Infrared Science
Archive, which is operated by JPL/CalTech, under contract with NASA; the Canadian Astronomy
Data Centre, which is operated by the Herzberg Institute of Astrophysics, National Research Council
of Canada; the SIMBAD database, operated at CDS, Strasbourg, France; NASA’s Astrophysics Data
System Service; and the Guide Star Catalog-II.
iii
Abstract
THE LUMINOSITY FUNCTION OF LOW-MASS STARS AND
BROWN DWARFS
Kelle Lin Cruz
Iain Neill Reid
We present a search for low-mass stars and brown dwarfs in the Solar Neighborhood using the Two
Micron All-Sky Survey (2MASS) Second Incremental Data Release. We have created a statistically
robust, volume-limited sample of M7–L8 dwarfs within 20 pc of the Sun using near-infrared colorcolor and color-magnitude constraints. We detail the construction of this sample, dubbed 2MU2,
and extensive, low-resolution far-red spectroscopic follow-up of candidates. These spectroscopic observations yield spectral type estimates which enable us to confirm candidates as nearby ultracool
dwarfs. Spectral type is used as a predictor of MJ , which is combined with 2MASS J-band photometry to obtain spectrophotometric distances. In the course of this program, we have discovered
of 261 late-M dwarfs and 94 L dwarfs—56 of these are within 20 pc, more than doubling the local
census. We combine these data with previously known objects to make the first, statistically robust
estimate the luminosity function of ultracool dwarfs in the Solar Neighborhood. This result is the
first quantitative measurement of the turnaround in the luminosity function of ultracool dwarfs at
faint magnitudes and is a confirmation of theoretical predictions. Finally, we discuss the implications
of this work and our future prospects.
iv
Contents
Acknowledgements
ii
Abstract
iv
List of Tables
vii
List of Figures
ix
1 Introduction
1.1 History of Discovery and the Extensions of the Spectral Sequence . . . . . .
1.1.1 Beginnings to M6.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1.2 Late-M Dwarfs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1.3 Optical and Near-Infrared Wide-Sky Surveys . . . . . . . . . . . . .
1.1.4 L Dwarfs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1.5 T Dwarfs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1.6 Y Dwarfs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Physical and Observable Properties of Low-Mass Stars and Brown Dwarfs .
1.2.1 Formation and Evolution . . . . . . . . . . . . . . . . . . . . . . . .
1.2.2 Atmospheric Properties . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 The Luminosity and Mass Functions of Low-Mass Stars and Brown Dwarfs
2 Meeting the Cool Neighbors. III. Spectroscopy of Northern
2.1 Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Target Selection . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4 Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5.1 Metallicity . . . . . . . . . . . . . . . . . . . . . . . . .
2.5.2 Absolute Magnitudes and Derived Distances . . . . . . .
2.6 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6.1 Additions to the Nearby-Star Sample . . . . . . . . . .
2.6.2 Possible Subdwarfs: LP 410-38 & LP 702-1 . . . . . . .
2.6.3 Chromospheric Activity . . . . . . . . . . . . . . . . . .
2.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Meeting the Cool Neighbors.
3.1 Abstract . . . . . . . . . . .
3.2 Introduction . . . . . . . . .
3.3 The 2MU2 Sample . . . . .
V.
. .
. .
. .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1
2
3
4
6
7
8
9
9
10
10
11
NLTT Stars
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
. . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
24
25
25
26
27
27
28
29
30
30
31
31
32
.
.
.
.
.
.
.
.
.
.
.
A 2MASS-Selected Sample of Ultracool Dwarfs
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
v
54
55
55
57
3.4
3.5
3.6
3.7
3.8
3.3.1 Refining the Faint Portion of the 2MU2 Sample
3.3.2 The Brightest Candidates . . . . . . . . . . . .
Observations . . . . . . . . . . . . . . . . . . . . . . .
Results . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5.1 Spectral Types . . . . . . . . . . . . . . . . . .
3.5.2 Absolute Magnitudes and Distances . . . . . .
Interesting Individual Objects . . . . . . . . . . . . . .
3.6.1 L Dwarfs within 10 pc . . . . . . . . . . . . . .
3.6.2 Brown Dwarfs . . . . . . . . . . . . . . . . . .
3.6.3 Active Objects . . . . . . . . . . . . . . . . . .
3.6.4 Young Objects . . . . . . . . . . . . . . . . . .
3.6.5 Two Blue L Dwarfs . . . . . . . . . . . . . . .
3.6.6 LP 775-31 & LP 655-48 . . . . . . . . . . . . .
Sample Characteristics and Preliminary Luminosity
Function4 . . . . . . . . . . . . . . . . . . . . . . . . .
Conclusions . . . . . . . . . . . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
59
60
62
63
64
65
65
65
66
66
66
67
67
. . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . .
68
70
4 Meeting the Cool Neighbors. IX. The Luminosity Function
Ultracool Dwarfs
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 The 2MU2 Sample . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3 Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5 The Luminosity Function . . . . . . . . . . . . . . . . . . . . . . .
4.5.1 Malmquist Bias . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.2 Incompleteness . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.3 Unresolved Binary Systems . . . . . . . . . . . . . . . . . .
4.6 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.1 The Luminosity Function . . . . . . . . . . . . . . . . . . .
4.6.2 Constraints on the Mass Function . . . . . . . . . . . . . .
4.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
of M7–L8 Type
110
. . . . . . . . . . 111
. . . . . . . . . . 111
. . . . . . . . . . 112
. . . . . . . . . . 113
. . . . . . . . . . 113
. . . . . . . . . . 114
. . . . . . . . . . 114
. . . . . . . . . . 117
. . . . . . . . . . 118
. . . . . . . . . . 118
. . . . . . . . . . 119
. . . . . . . . . . 119
5 Future Work and Summary
5.1 Completing the Census . . . . . . . . . . . . . . . . . . .
5.1.1 Finish Follow-up Observations of 2MU2 Sample .
5.1.2 2MASS All-Sky Release . . . . . . . . . . . . . .
5.1.3 Companion Searches . . . . . . . . . . . . . . . .
5.2 Understanding Brown Dwarf Atmospheres . . . . . . . .
5.3 Discovering the Lowest-Mass Brown Dwarfs with Spitzer
5.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . .
A The
A.1
A.2
A.3
Brightest Sources
Introduction . . . . . . . . . . . . . .
Identifications . . . . . . . . . . . . .
Discussion . . . . . . . . . . . . . . .
A.3.1 The Reddest Candidates . . .
A.3.2 Cross-checks Against Existing
A.4 Conclusions . . . . . . . . . . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
Catalogs
. . . . . .
Bibliography
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
141
141
141
141
142
142
143
144
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
147
147
147
148
148
151
151
169
vi
List of Tables
1.1
Properties of Ultracool Dwarfs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.1
2.2
2.3
2.4
2.5
2.6
Previously Known Objects in Our Sample of NLTT Targets
Data for Targets Included in NLTT Sample 1 . . . . . . . .
Data for Targets Not Included in NLTT Sample 1 . . . . .
Regions That Define the Spectroscopic Indices . . . . . . .
Spectral Indices of NLTT Targets and Standards . . . . . .
Activity of NLTT Sample . . . . . . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
44
45
47
49
50
53
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12
3.13
3.14
Accounting of Steps to Create the 2MU2 Sample . . . . . . . . . .
Cataloged Clouds . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Uncataloged Reddening Regions . . . . . . . . . . . . . . . . . . .
Accounting of Steps to Refine J > 9 Portion of the 2MU2 Sample .
Previously Known Cool Dwarfs Recovered in the 2MU2 Sample . .
Late-type Dwarfs with J < 9 . . . . . . . . . . . . . . . . . . . . .
M7–L8 Dwarfs Discovered Within 20 pc . . . . . . . . . . . . . . .
M7–L8 Dwarfs Discovered Outside 20 pc . . . . . . . . . . . . . . .
Early-type M Dwarfs Discovered Within 20 pc . . . . . . . . . . .
Early-type M dwarfs Discovered Outside 20 pc . . . . . . . . . . .
Young Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spectroscopically Confirmed Giants . . . . . . . . . . . . . . . . . .
Spectroscopically Confirmed Carbon Stars . . . . . . . . . . . . . .
MJ /Spectral Type Calibration Data . . . . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
84
85
85
86
87
91
92
95
101
102
104
105
107
108
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
M6–L8 Dwarfs Discovered Within 20 pc . . . . . . . . . . . . . . . . . . . . . .
M7–L8 Dwarfs Discovered Outside 20 pc . . . . . . . . . . . . . . . . . . . . . .
Early-Type M Dwarfs Discovered Outside 20 pc . . . . . . . . . . . . . . . . . .
Low Gravity Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spectroscopically Confirmed Giants . . . . . . . . . . . . . . . . . . . . . . . . .
Spectroscopically Confirmed Carbon Stars . . . . . . . . . . . . . . . . . . . . .
Objects Used to Estimate the Luminosity Function (The 20 pc 2MU2 Sample)
Percentage of Optical Follow-up Observations Completed . . . . . . . . . . . .
Corrections for Observational Incompleteness . . . . . . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
128
129
132
133
134
135
136
139
140
A.1
A.2
A.3
A.4
A.5
J < 9 Sources with IRAS Catalog Counterparts
J < 9 Sources with Stellar Counterparts . . . .
Carbon stars . . . . . . . . . . . . . . . . . . .
Miras and Long-period Variables . . . . . . . .
Semi-regular Variables . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
155
157
160
161
163
vii
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
A.6 Other Late-type Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
A.7 J < 9 Sources Without a Cataloged Counterpart . . . . . . . . . . . . . . . . . . . . 165
viii
List of Figures
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
M dwarf spectral sequence . . . . . . . . . . . . . . . . . . . . . . . . .
L dwarf spectral sequence . . . . . . . . . . . . . . . . . . . . . . . . .
T dwarf spectral sequence . . . . . . . . . . . . . . . . . . . . . . . . .
Near-infrared spectra of M and L dwarfs . . . . . . . . . . . . . . . . .
Near-infrared color-magnitude and color-diagrams for ultracool dwarfs
Effective temperature evolution of brown dwarfs . . . . . . . . . . . .
V -band luminosity function of nearby stars . . . . . . . . . . . . . . .
Mass function estimate of the Solar Neighborhood . . . . . . . . . . .
Luminosity function of T dwarfs . . . . . . . . . . . . . . . . . . . . .
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
Color-color criteria for NLTT Sample 1 . . . . . . . . . . . . . . . .
Bandstrengths for NLTT targets . . . . . . . . . . . . . . . . . . . .
Spectral type/spectral index calibrations . . . . . . . . . . . . . . . .
Absolute magnitude/spectral index calibrations . . . . . . . . . . . .
Spectrum of LP 647-13, M9 . . . . . . . . . . . . . . . . . . . . . . .
Spectrum of LP 763-3, M7 . . . . . . . . . . . . . . . . . . . . . . . .
Spectra of two subdwarfs, an M6 dwarf, and a late-type intermediate
J-band bolometric correction . . . . . . . . . . . . . . . . . . . . . .
Distribution of chromospheric activity amongst NLTT Sample 1 . .
3.1
Color-magnitude diagram for low-mass stars with trigonometric parallax measurements shifted to 20 pc and a typical 1◦ 2MASS field with our selection criteria . . .
Color-color diagram for the same data as Figure 3.1 and our selection criteria . . . .
Color-magnitude diagram for GKM dwarfs and L dwarfs with known parallaxes shifted
to 20 pc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Color-magnitude and color-color diagrams for surviving targets . . . . . . . . . . . .
Color-color diagram for bright ultracool candidates . . . . . . . . . . . . . . . . . . .
Color-magnitude and color-color diagrams for the all of the cool dwarfs present in
Paper V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MJ /spectral type calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spectra for some of the interesting objects . . . . . . . . . . . . . . . . . . . . . . . .
Spectra of candidate young objects and M7 and M8 spectral standards . . . . . . . .
Spectra of candidate young object 2M 0608 and the M9 standard LHS 2065 . . . . .
Stacked histogram of the spectral type of all the dwarfs M5 and later in our sample
and distance distributions of the M7–L8 dwarfs . . . . . . . . . . . . . . . . . . . . .
Preliminary field luminosity functions and spectral type distribution for dwarfs within
20 pc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Color-magnitude for the all 2MU2 targets not presented in Paper V . . . . . . . . .
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12
3.13
ix
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
14
15
16
17
18
19
20
21
22
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
subdwarf
. . . . . .
. . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
34
35
36
37
38
39
40
41
42
71
72
73
74
75
76
77
78
79
80
81
82
83
4.1
4.2
4.3
4.4
4.5
4.6
4.7
Status of spectroscopic follow-up of the 2MU2 sample . . . . . . . . . . . . .
Color-magnitude and color-color diagrams of the 2MU2 sample . . . . . . . .
J-band luminosity function of ultracool dwarfs . . . . . . . . . . . . .
Volume completeness of the 2MU2 sample . . . . . . . . . . . . . . . . . . . .
Color-magnitude and color-color diagram of ultracool dwarfs with parallaxes
J-band luminosity function for the 2MU2 and 8 pc samples . . . . . . . . . .
Model luminosity functions that best fit the data . . . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
121
122
123
124
125
126
127
5.1
Artist rendition of M, L, and T Dwarfs and Jupiter . . . . . . . . . . . . . . . . . . . 145
A.1 Celestial and near-infrared color-magnitude and color-color distributions for the 2MU2
bright sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
A.2 Celestial and near-infrared color-magnitude and color-color distributions for the sources
in the 2MU2 bright sample that matched against known carbon stars, Miras, semiregular variables, and other late-type stars . . . . . . . . . . . . . . . . . . . . . . . . 153
A.3 Celestial and near-infrared color-magnitude and color-color distributions for the sources
in the 2MU2 bright sample with no counterpart listed by SIMBAD . . . . . . . . . . 154
x
Chapter 1
Introduction
The study of brown dwarfs and extrasolar giant planets is very much germane to
understanding the occurrence and properties of planetary systems, the baryonic content
and chemical evolution of the cosmos, and the relationship (in both genesis and physical
properties) between stars and objects not massive enough ever to become stars. By
detecting and characterizing brown dwarfs and giant planets, we extend our knowledge
of the cosmos from the ubiquitous macroscale of stars ever closer to the instinctively
appealing, and human, scale of worlds like our own.
—— Burrows et al. (2001)
Low-mass stars and brown dwarfs are ubiquitous—they are likely to be the most common
objects in the Milky Way, yet observing them has only become possible in the last twenty years.
With the development of near-infrared detectors, these objects were finally able to be discovered in
fairly large numbers. However, when the work described in this dissertation was begun, the catalog
of known low-mass objects were drawn from small portions of the sky and were subject to various
biases and selection effects. As a result, it was difficult to use these objects as a basis for statistical
study and to answer pressing questions such as: How numerous are they? What is their distribution
of luminosity, mass, and metallicity? What observational properties trace these physical properties?
The answers to these questions are needed to begin the task of identifying the differentiating traits
of stars, brown dwarfs, and planets. The aim of the work presented in the following chapters is the
creation of a volume-limited, statistically complete sample of objects that span the stellar/brown
dwarf boundary that can be used to study the detailed properties of these low-mass objects. In
particular, we will use this sample to estimate the field luminosity function of low-mass stars and
brown dwarfs. First, however, the stage must be set and the characters introduced.
The two major players in this story are low-mass stars and substellar-mass objects, originally
called “black dwarfs” by Kumar (1963), but were renamed “brown dwarfs” by Tarter (1974). Lowmass stars are just that, stars at the end of the stellar mass (and temperature) scales. Brown dwarfs,
on the other hand, are objects which form in the same way stars do, through gravitational collapse
1
of dense gas within in a cloud core, but do not accrete enough mass (M ∼ 0.075 M¯ ) to maintain
hydrogen burning in their core and thus do not reach the main sequence. Unlike stars, which reach
an equilibrium temperature and remain there for billions of years, brown dwarfs gradually cool and
fade over time. These substellar objects were theoretically hypothesized to exist in the early sixties
independently by both Kumar (1963) and Hayashi & Nakano (1963), however the search for them
did come into full swing until the mid-1980s.
This introductory chapter places the remainder of the dissertation in historical context. In
§ 1.1, the first discoveries of low-mass stars and brown dwarfs, and the subsequent extensions of the
spectral sequence, are recounted. The physical and observable properties of ultracool dwarfs are
described in § 1.2. Finally, in § 1.3 the work done on the luminosity and mass functions of ultracool
dwarfs prior to this dissertation is summarized.
1.1
History of Discovery and the Extensions of the Spectral
Sequence
It is very difficult to distinguish brown dwarfs from low-mass stars since the delineating factor is
mass, a quantity rarely measured in astronomy. As a result, much of the following discussion centers
around spectral types rather than “stars” and “brown dwarfs.” Spectral type is a classification
scheme based on the morphology of the atomic and molecular features seen in the spectrum of a
celestial body. For many objects, the spectral type is the only physical property which can be
directly measured. In the absence of a parallax measurement, absolute magnitude, temperature,
age, and mass can be estimated only with the aid of theoretical models. The spectral sequence is
also a temperature sequence with O stars at the hot extreme and M dwarfs at the other, as was first
suggested by Vogel (1874) and shown by Wilsing & Scheiner (1909). In the case of low-mass stars
and brown dwarfs, while it is difficult to compare their masses and ages, we can say with certainty
that an L dwarf is cooler than an M dwarf and a T dwarf is cooler than an L dwarf. (Current models
predict that all objects later than ∼L3 are brown dwarfs while types ∼M6 to L2 are a mix of both
stars and young brown dwarfs.)
This section is a review of the exploration of the end of the main sequence and the discovery
of brown dwarfs. We follow the story of how the spectral sequence was extended from Cannon’s
original coolest classification of Mc to include the mid- and late-M dwarfs by the early 1990s, and
then eventually down to the “L” dwarfs in 1999, and the “T” dwarfs in 2002. We also describe the
near-infrared and optical surveys that made the discovery of a large number of very cool objects
possible. The history recounted below is compiled from a number of sources: Hearnshaw’s (1986)
history of astronomical spectroscopy; the textbook written by Reid & Hawley (2000) on low-mass
stars and brown dwarfs; extremely thorough papers co-written by Davy Kirkpatrick (Kirkpatrick,
Henry, & McCarthy 1991; Kirkpatrick, Henry, & Simons 1995); and correspondence with Neill Reid,
Jim Liebert, Adam Burgasser, and Davy Kirkpatrick.
2
1.1.1
Beginnings to M6.5
We pick up the story of spectral classification with Pickering’s stellar spectroscopy program at
the Harvard College Observatory, funded by Ana Palmer Draper to honor the memory of her husband
Henry Draper, who first successfully photographed a stellar spectrum. The first major program as
part of the Draper Memorial was the compilation of 10,351 spectra in the Draper Catalog of Stellar
Spectra (Pickering 1890). These spectra were classified by Williamina Fleming on a system with
types A–N. Antonia Maury, the niece of Henry Draper, used a more detailed classification system
utilizing twenty-two roman numerals for the study of the northern bright stars (Maury & Pickering
1897).
Annie Jump Cannon worked on the classification of the southern bright stars. She chose not to
adopt the system used by Maury, and instead revised the original classification scheme devised by
Fleming to the familiar OBAFGKM system (Cannon & Pickering 1901). In addition, she developed
the decimal subdivision of the types using numbers (i.e., B5 meaning halfway from B to A). However,
the M class was subdivided into types Ma–c. This system was used to classify the 225,300 stars
that make up the Henry Draper (HD) Catalog (same guy, different catalog) and despite several
competing classification schemes, the Harvard system was widely accepted by 1913. It was formally
approved at the first meeting of the newly formed International Astronomical Union (IAU) in Rome,
in May 1922. In addition to an extensive list of revisions, the committee relabeled the Ma-c classes
on a decimal system from M0–M8.
While the Harvard system provided an extremely useful way to characterize spectra, it has
the drawbacks of depending on the relative strengths of atomic lines and molecular bands and of
lumping spectra with a wide range of properties into one class. The “MK system” solves these
problems by creating a grid of spectral standards to which program stars were compared. The
general classification scheme is described in Morgan, Keenan, & Kellman (1943) and the standards
are listed in Johnson & Morgan (1953). The list of standards sufficiently define the MK system over
the range O9–M2 with Barnard’s Star fixed at type M5. This system is still in general use, although
it has never been formally adopted by the IAU.
There were several competing systems for classifying objects later than M2. The two most
widely used were the Yerkes (Morgan 1938; Kuiper 1942) and Mt. Wilson (Joy 1947; Joy & Abt
1974) systems. The fundamental problems with these systems is that they are based on spectral
features significantly blueward of the peak of the M-dwarf emission where getting high signal-tonoise spectra is difficult. A system to classify mid-M dwarfs was not widely adopted until Boeshaar
(1976) extended the sequence to M6.5 using features as red as 6800 Å.
3
1.1.2
Late-M Dwarfs
Listed below, in chronological order of publication, are the objects that necessitated the extension of the M dwarf sequence past M6.5. The spectral type that the object was eventually assigned
is listed alongside its name.
VB 10, M8 — van Biesbroeck (1944) reported the discovery of VB 10 in a six paragraph paper as
a low luminosity companion to BD +4◦ 4048. Because the primary was a well known nearby
star with a measured parallax, the absolute magnitude for VB 10 was easily derived. van
Biesbroeck reported that the object is “three magnitudes fainter than the lower limit known
up to now, which was held by Wolf 359.” Wolf 359 is typed as M5.5.
VB 8, M7 — Fifteen years after the discovery of VB 10 was announced, van Biesbroeck (1961)
reported other low-luminosity objects that turned up as common proper motion companions
to known nearby stars. This list included VB 8 as the second faintest object after VB 10.
These two objects remained the coolest stars known for the following twenty years.
RG 0050-2722, M8: — Reid & Gilmore (1981) discovered this object in their search for low-mass
stars using purely photometric techniques. It is fainter than VB 8, but not VB 10, and thus
became the second coolest star known. (Partly due to its low declination at −30◦ , this object
is still not completely understood. Its spectrum display features characteristic of both M8 and
M9 dwarfs and its colors are significantly bluer than other M8s.)
LHS 2924, M9 — Probst & Liebert (1983) identified LHS 2924 as a cool dwarf through spectroscopic follow-up of red stars in Luyten’s catalog of stars with proper motions exceeding 0.00 5
annually (Luyten 1979, LHS). With significantly redder colors and a fainter absolute magnitude estimate, LHS 2924 took the title of “the dwarf of lowest luminosity” from VB 10 after
a reign of thirty-nine years. It was also one of the first objects to be advertised as a possible
brown dwarf.
LHS 2397a, M8 — This object was identified by Probst and Bessell as a red object with colors
similar to LHS 2924 (Liebert, Boroson, & Giampapa 1984). (Now recognized as a binary with
a late-L type companion (Freed, Close, & Siegler 2003).)
(VB 8B) — McCarthy, Probst, & Low (1985) announced the detection of a very cool companion to
VB 8 using one-dimensional speckle scans. Its extremely low-luminosity, along with estimates
placing its mass just below the hydrogen burning limit, resulted in VB 8B to be accepted as
the first clear brown dwarf discovery. Unfortunately, this detection did not hold up under
rigorous scrutiny and by 1987, VB 8B was recognized as an observational artifact. Regardless,
this “discovery” played an important role in advancing brown dwarf astronomy by prompting
the first conference entirely dedicated to substellar objects held at George Mason University
in Fairfax, Virginia in October of 1985.
4
LHS 2065, M9 — This object was identified by Bessel as a late-type dwarf through spectroscopic
follow-up of red objects in the LHS catalog (Reid 1987; Hawkins & Bessell 1988).
Gl 569B, M8.5 — Skrutskie, Forrest, & Shure (1987) uncovered this companion to Gl 569A during a near-infrared imaging survey around nearby stars (Forrest, Shure, & Skrutskie 1988).
(Now recognized as M8.5/M9 brown dwarf binary, making Gl 569 a tertiary system (Kenworthy
et al. 2001; Lane et al. 2001).)
Based on these first discoveries, Kirkpatrick, Henry, & McCarthy (1991) extended the spectral
sequence to M9 utilizing the far-red (6300–9000Å) part of the spectrum. The M dwarf spectral
sequence is shown in Figure 1.1. Concurrently, Bessell (1991) also proposed a classification scheme
for the late-M dwarfs. However, Bessell did not include a list of spectral standards and his scheme
was based more on the features characteristic of giants rather than dwarfs. As a result, the “KHM
system” was widely adopted.
By the end of 1995, twenty-one objects were known with spectral types M7 and cooler (Kirkpatrick, Henry, & Simons 1995), two of which were clearly later than type M.
GD 165B, L4 — Becklin & Zuckerman (1988) found this object in a search for low-mass companions around white dwarfs. GD 165A has a known distance and the absolute magnitude
inferred for the companion was close to the brown dwarf regime. While the infrared spectrum
of GD 165B is not dramatically different from that of late-M dwarfs, the optical spectrum is
relatively smooth and lacks most of the features characteristic of M dwarfs (Jones et al. 1994;
Kirkpatrick, Henry, & Liebert 1993). The explanation for these unusual spectral features was
not immediately apparent. The spectrum is affected by overflow light from the white dwarf
primary and it was suggested that during the primary’s asymptotic giant branch phase, the
atmosphere of the companion was polluted. As a result, GD 165B was considered a “unique
oddity.”
Gl 229B, T6.5 — This object was discovered by Nakajima et al. (1995) as a companion to Gl 299A,
one of the nearest M dwarfs with a distance of 5.7 pc. The extremely low luminosity of the
companion, combined with the detection of methane in the near-infrared spectrum (as predicted by Tsuji (1964)) made its status as a brown dwarf unquestionable (Oppenheimer et al.
1995).
At this time, there were also successful brown dwarf searches taking place in young clusters and
as a result, Gl 229B is in competition with several other objects for the title of “first brown dwarf.”
Studies of low-mass objects in young clusters are extremely important since young brown dwarfs
are more luminous than their older counterparts found in the field. In addition, since clusters have
reliable age estimates, these discoveries can place strong constraints on models. However, since this
dissertation concentrates on low-mass stars and brown dwarfs in the field, a discussion of the results
from young clusters is not included here.
5
1.1.3
Optical and Near-Infrared Wide-Sky Surveys
The discoveries that motivate the rest of the story are almost exclusively attributed to three,
wide-sky, near-infrared and optical surveys. Due to the large impact of these projects on the field
of low-mass stars and brown dwarfs, we briefly interrupt the narrative to summarize them here.
1.1.3.1
DENIS
The Deep Near-Infrared Survey (Epchtein et al. 1999, DENIS) is an all-southern sky (−88◦ <
δ < 2◦ ) survey conducted by a European consortium. Beginning in 1995 and ending in 2001, the
ESO 1-m telescope in La Silla in Chile was used to image approximately 20000 sq. deg. in three
passbands: I, J, and KS (0.82, 1.25, and 2.15 µm). The survey goes moderately deep, achieving
a signal-to-noise ratio of ∼10 at I ∼ 17.5, J ∼ 16, and KS ∼ 13. The first data release was in
1998 December followed by a second in 2003 May with 11000 sq. deg. of data. The full catalog is
expected later this year.
1.1.3.2
2MASS
The Two Micron All-Sky Survey (Skrutskie 2001, 2MASS) is an all-American collaboration
between the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC)
and is funded primarily by NASA and the NSF. Two highly automated 1.3-m telescopes, one on
Cerro Panchon in Chile and the other on Mt. Hopkins in Arizona, were used to image the entire
sky at J, H, and KS (1.24, 1.55, and 2.16 µm). The sensitivity is similar to DENIS, reaching a
signal-to-noise ratio of ∼10 at J ∼ 16.5, H ∼ 15.8, and KS ∼ 14.5. Observations began in Spring
1997 and finished in Spring 2001, with the first data released in 1998 December and the All-Sky
Release in 2003 March. The data products include a point-source catalog, extended-source catalog,
and image atlas.
1.1.3.3
SDSS
The Sloan Digital Sky Survey (York et al. 2000, SDSS) is run by and international collaboration
and has received a substantial amount of financial support from its namesake, the Alfred P. Sloan
Foundation, and various other private and governmental organizations. The goal of this survey is a
very deep optical survey of approximately one-quarter of the sky. Thirty CCDs on a 2.5-m telescope
at Apache Point Observatory in New Mexico are used to obtain data in five passbands, u, g, r, i,
and z (3551, 4686, 6165, 7481, and 8931 Å). In addition, two fiber spectrographs, each with a blue
and red channel, simultaneously collect moderate resolution spectra (λ/∆λ = 1800) covering 3800–
9200 Å. As of 2004 March, approximately 3000 sq. deg. of data have been made public over three
releases (EDR, DR1, and DR2). The most recent prediction is that 7700 sq. deg. of photometry
and 7000 sq. deg. of spectroscopy will be made available by July 2006 over three more data releases.
6
1.1.4
L Dwarfs
With the first results from DENIS and 2MASS, GD 165B did not remain unique for very long.
2M 0345, L0 — Kirkpatrick, Beichman, & Skrutskie (1997) announced the discovery of
2MASSP J0345432+254023, which seemed to have spectral features between an M9 and
GD 165B. In addition, they also identified eight additional late-M dwarfs, a 30% increase
in the census. This work was done with the 2MASS Prototype Camera and hinted at the vast
number of objects 2MASS would be able to identify once the whole sky was imaged in the
near-infrared.
Kelu 1, L2 — Kelu-1 was identified in the Calan-ESO proper-motion survey of the southern hemisphere (Ruiz, Leggett, & Allard 1997). This was the first object clearly later than type M and
where, unlike GD 165B, no explanation other than low temperature could be proposed to
account for the observed spectral features. In the language of the Mapuche people of Chile,
kelu means “red.”
DENIS 1058, L3; DENIS 1228, L5; DENIS 0205, L7 — Delfosse et al. (1997) reported the
discovery of three candidate brown dwarfs in their preliminary analysis of DENIS data for 1%
of the sky in a “mini-survey.”
Twenty from 2MASS — Kirkpatrick et al. (1999) used the 2MASS working database to select
likely brown dwarfs and obtained spectroscopic follow-up with Keck. This work resulted in
twenty new discoveries and the definition of the new “L” spectral sequence as shown in Figure 1.2. These twenty, and the five objects listed above, fit into the L classification scheme,
however, Gl 299B remained in a class of its own, already dubbed “T.”
Five from DENIS — Martı́n et al. (1999) also proposed a classification scheme for L dwarfs using
sixteen objects from both DENIS and 2MASS. That scheme, however, is tied to a model-based
temperature scale, with each subclass stepping 100 K in effective temperature. Following the
tradition that spectral classification be based purely on the morphology of the spectra, the
scheme of Kirkpatrick et al. (1999) has become widely accepted.
These discoveries were followed by a multitude from the 2MASS working database and the first
results from SDSS, bringing the total of known L dwarfs to just over two hundred by the year 2002
(Kirkpatrick et al. 2000; Gizis et al. 2000; Schneider et al. 2002; Hawley et al. 2002). At the time of
this writing, approximately four hundred L dwarfs are known—most of the additions were uncovered
as part of the program described in this dissertation and are listed in various tables included in the
following chapters.
7
1.1.5
T Dwarfs
With Gl 229B as glaring evidence of an even cooler class of objects, the search for T dwarfs
was concurrent with the L dwarf search. Where 2MASS unleashed a flood of L dwarf discoveries,
the pace of T dwarf discoveries more resembles a steady trickle because of their intrinsically fainter
magnitudes and unusual colors.
SDSS 1624, T6; SDSS 1346, T6 — Strauss et al. (1999) and Tsvetanov et al. (2000) reported
the discovery of two T dwarfs found in 400 sq. deg. (1% of the sky) of SDSS commissioning
data. These were the first T dwarfs found after Gl 229B and both are in the field.
Four from 2MASS, all T6s — Burgasser et al. (1999) found four new T dwarfs (and recovered
SDSS 1624) in 1800 sq. deg. of the 2MASS First Incremental Release and the working database.
NTTDF J1205-0744, T6: — Cuby et al. (1999) reported the fortuitous discovery of this object
in the ESO New Technology Telescope (NTT) Deep Field, with a magnitude limit of KS = 22.8
over a 5 × 5 arcminute field. The object is very distant at d ∼ 90 pc.
2MASS 0559, T5; Gl 570D, T8 — Burgasser et al. (2000a,b) found both of these objects in
the 2MASS working database. Gl 570D, part of the Gl 570ABC system, became the second
T-type companion as well as the coolest known brown dwarf.
Three from SDSS, T1–T3 — The first discoveries of warm T dwarfs were made with SDSS
because early-T dwarfs can be easily identified by their extremely red (i − z) color (Leggett
et al. 2000). In 2MASS, with only JHK photometry, these objects are much more difficult to
pick out since their near-infrared colors are similar to those of common M dwarfs.
Eleven from 2MASS — Burgasser et al. (2002) used eleven additional 2MASS discoveries and
the three early-T dwarfs from SDSS to establish a T dwarf classification scheme in the nearinfrared. Similar to the necessity to go to redder wavelengths to get high enough signal-to-noise
observations with which to classify the M and L dwarfs, T dwarfs are best classified in the
near-infrared. The T dwarf spectral sequence on this system is shown in Figure 1.3.
Eight from SDSS — Independently, Geballe et al. (2002) also use the previously known T dwarfs
along with eight new SDSS objects to establish a similar, but different, T dwarf spectral
sequence. These authors also endeavor to create a near-infrared scheme for L dwarfs, thus
allowing L and T dwarfs to be on the same system. Both the Burgasser and Geballe systems
are in wide use.
Because brown dwarfs evolve through the L dwarf sequence faster than the T sequence, we
expect to find more T dwarfs than L dwarfs. However, due to their extreme low luminosities and
colors that overlap with other populations (e.g., M dwarfs and asteroids), T dwarfs are still fairly
8
rare, with just more than fifty known. For those keeping track, the coolest currently known object
is 2MASS 0415, a T8 dwarf (Burgasser et al. 2002, T9 on the Geballe system) with a temperature
estimate of a mere 600–800 K (Vrba et al. 2004; Golimowski et al. 2004).
1.1.6
Y Dwarfs
There is little doubt that cooler objects exist—low-mass brown dwarfs evolve past the T sequence in 100 million years. These objects are sometimes referred to as “cooler than type-T,” for
the obvious reason; “water dwarfs,” because they are expected to have water clouds; or “Y dwarfs,”
as proposed by Davy Kirkpatrick since they will likely require yet another new spectral class. Technically, since no objects cooler than type T have been found, and their spectral properties are not
known, a new spectral class definition cannot exist.
Since these objects have not yet been discovered, there is not much known about them. However,
there have been several theoretical insights such as the presence of water clouds and ammonia in
their spectra (Burrows, Sudarsky, & Lunine 2003; Martı́n et al. 2001). In addition, in a continuation
of the theme that as we probe cooler temperatures, we need to observe at redder wavelengths, there
is great hope that these objects will be uncovered with the Spitzer Space Telescope—Y Dwarfs,
they’re the next cool thing.
1.2
Physical and Observable Properties of Low-Mass Stars
and Brown Dwarfs
The properties of brown dwarfs, especially their atmospheres, is a very rich subject, and in this
section we provide only a brief overview. This topic has been addressed in great detail in both the
Burrows et al. (2001) Reviews of Modern Physics article and the Reid & Hawley (2000) textbook,
New Light on Dark Stars.
As stated before, brown dwarfs form like stars except, because of their low mass, they do not
reach a long-lived stable state like main sequence stars. To paint the picture with broad strokes,
brown dwarfs are fully-convective, have high-pressures, are mostly supported by electron degeneracy,
have photospheres depleted of heavy elements, and gradually cool with time. The far-red and nearinfrared spectra for M, L, and T dwarfs are shown in Figures 1.1–1.4. As described in more detail
below, spectra of M dwarfs are characterized by molecular absorption bands of metal-oxides and
metal-hydrides. In L dwarfs, the metal-hydrides and alkali lines become more dominate. T dwarfs
are dominated by features due to water and methane. The near-infrared color-color and colormagnitude diagrams of late-type stars and brown dwarfs are shown in Figure 1.5—M and L dwarfs
have very red colors while T dwarfs have blue near-infrared colors. The effective temperatures and
the molecules that dominate the spectra of ultracool dwarfs are listed in Table 1.1.
9
1.2.1
Formation and Evolution
As protostellar (and protosubstellar) objects collapse, the core temperature and density increase.
For traditional stars, with masses greater than the “hydrogen-burning minimum mass” (HBMM),
the core temperature gets high enough to ignite hydrogen fusion, the resulting thermal and radiative
pressure halts further collapse, the power generated by the fusion balances the photon luminosity
loses from the surface, and the star settles onto the main sequence.
Lower-mass objects must collapse to higher densities to reach temperatures high enough to
ignite hydrogen fusion. Below M ∼ 0.1 M¯ , the density becomes so high that electron degeneracy
begins to play a significant role. The resulting core pressure (pushing outward as the electrons
try to increase their separation), halts further gravitational contraction. If this happens before the
core temperature is high enough to support enough hydrogen fusion to counterbalance radiative
losses, the object becomes a brown dwarf. This occurs for objects less massive than the HBMM of
∼ 0.075 M¯ (assuming solar metallicity). The effective temperature evolutionary tracks for low-mass
stars and brown dwarfs are shown in Figure 1.6.
The radii of star-like objects decreases significantly with mass from 1 to 0.1 M¯ , where electron
degeneracy becomes the dominant source of support. For older objects, with masses ranging from
0.3 MJupiter to 0.07 M¯ , the radii are independent of mass to within about 30% due to the balancing
of the effects due to Coulomb repulsion (R ∝ M 1/3 ) and electron degeneracy (R ∝ M −1/3 ). Thus,
late-type stars and brown dwarfs are all about the same size as Jupiter. Fortuitously, the constancy
of brown dwarf radii enables gravity to be an excellent mass indicator. Thus, in some cases, gravity
sensitive spectral features can be used to distinguish low-mass stars from young brown dwarfs.
Another important mass indicator is lithium. While brown dwarfs do not generate enough
power through core hydrogen burning to balance the radiative losses at the surface, they can have
partial and temporary phases of thermonuclear burning. In particular, objects more massive than
∼ 0.06 M¯ burn a significant amount their lithium fraction. Note that this mass is just below the
HBMM at 0.075 M¯ . As a result, since these objects are fully convective, if the atomic lithium line at
6708 Å is detected in older objects, they must be less massive than 0.06 M¯ and thus undoubtedly a
brown dwarf. This “lithium test” is one of the few observational indicators of substellarity for early-L
dwarfs. However, the feature has a small equivalent width and many times cannot be distinguished
from the noise. A robust lithium detection is shown in the L6 spectrum plotted in Figure 1.2.
1.2.2
Atmospheric Properties
Condensation and “rain out” play an important role in the atmospheric properties of cool dwarfs.
When the temperature of photosphere drops, molecules condense, changing from a gas to either a
solid grain or a liquid drop. Once in this form, the grains and/or droplets can rain out of the upper
atmosphere. While this mechanism is poorly understood, experience with planetary atmospheres
suggests that the condensates form a cloud layer of some finite thickness, presumably lower in the
10
Table 1.1.
Spectral Type
Properties of Ultracool Dwarfs
Temperature (K)
Dominate Elements
Late-M
2500–2800
TiO, VO
L Dwarfs
1400–2500
Na, K, FeH, CrH
T Dwarfs
700–1400
H2 O, CH3
Y Dwarfs
160–700
NH3
atmosphere where the higher temperature turns them back into a gas. Thus the higher layers in the
atmosphere, and most relevantly, the photosphere, become depleted of these condensates.
The spectra of late-M dwarfs, with photospheric temperatures ranging from 2500 to 2800 K,
are dominated by metal oxides, especially TiO and VO. Between 1800 and 2100 K, both of these
molecules, in addition to Ca and Al silicates, rain out. This ensures that the alkali metals, specifically
Na and K, are not sequestered in molecules but instead are present in their elemental from. Due to
the abundance of H2 , the natural widths of the K I doublet at 7665 and 7699 Å the Na D lines at
5890 Å are overwhelmed by collisional broadening and dominate the optical and far-red spectra of
both L and T dwarfs. Also present in the spectra of L dwarfs are metal hydrides (FeH and CrH) in
the far-red and H2 O and CO in the near-infrared.
At temperatures ∼1300–1500 K, the dominant carbon molecule changes from CO to CH4 , the
hallmark feature of the T dwarfs. This, combined with increasing water absorption in the J and H
bands and collision-induced H2 suppression of the K band, cause the near-infrared color of T dwarfs
to become bluer (Figure 1.5). Below 700 K, N2 turns into NH3 and below ∼500 K, H2 O condenses
into “water clouds”, signalling an, as yet unidentified, new spectral class.
The current understanding of the atmospheres of these objects is based on far-red and nearinfrared data, 0.6–2.5 µm. The recently christened Spitzer Space Telescope will greatly extend the
wavelength coverage and will undoubtedly lend greater insight into these complex environments,
and likely discover new ones.
1.3
The Luminosity and Mass Functions of Low-Mass Stars
and Brown Dwarfs
One of the best ways to accurately determine the luminosity function, and thus the mass
function, of low-mass stars and brown dwarfs is by using the local Solar Neighborhood as the
laboratory. (Another good way is to study low-mass populations in young clusters.) Because older
11
brown dwarfs have such intrinsically low luminosities, they need to be nearby in order for us to see
them, much less to study them in any detail. The main uncertainties that arise when measuring the
luminosity function are incompleteness at faint magnitudes, unresolved/unrecognized companions,
and inaccurate distance estimates. We discuss these issues in detail below.
• The census of the Solar Neighborhood is incomplete at the faintest luminosities for several
reasons, one of which is simply because faint objects are hard to see. In addition, these objects
emit most of their light at red wavelengths, where photograph plates are less sensitive. With
the advent of both CCDs and near-infrared detectors, these cool objects are easier to detect.
The primary goal of our NStars program, of which this dissertation is a part, is to complete the
catalog of low-mass stars in the Solar Neighborhood. However, the census remains incomplete
at types later than ∼L7.
• Approximately 40% of main sequence stars are in multiple systems; the current multiplicity
estimate for ultracool dwarfs is about 15% (Gizis et al. 2003; Bouy et al. 2003). The effects of
binarity influence luminosity function estimates of the Solar Neighborhood in several ways. On
the downside, unresolved multiple systems appear brighter than single objects and thus their
photometric is distance is underestimated, i.e., they appear to be closer than they actually are.
However, as demonstrated above, low-mass objects can be identified simply by looking around
known nearby stars. The catch is that uncovering companions is not always easy. In the case
of a low-luminosity companion to a brighter primary, blocking the light of the primary can be
difficult. Ultracool dwarf binaries have been shown to have separations less than 15 AU, and
thus high resolution observations are required. Furthermore, uncertainties still exist until all
objects in the sample have been checked for potential companions. We are involved in several
efforts to identify close companions to nearby ultracool dwarfs as described in § 5.1.3 and there
are many programs searching for low-mass companions, specifically planets, around solar-type
stars. However, we are unaware of any projects focused on uncovering companions to K or M
dwarfs.
• Where a trigonometric parallax is not available, distance estimates are based on photometric
calibrations. While these calibrations are fairly robust, they do not allow for intrinsic variations
in the luminosities of objects and yield inaccurate results for unresolved binary systems—a
parallax measurement is by far the preferred method of estimating distances to nearby objects.
Unfortunately, obtaining parallaxes is difficult and time consuming, requiring at least a one
year base-line. In addition, there are not that many programs currently doing astrometry and
the notion that measuring parallaxes is no longer “cutting-edge” is threatening its future. As a
result, trigonometric parallaxes are rare and most distance estimates are based on photometric
calibrations, where the uncertainties are inherently larger.
12
Initial studies of the Solar Neighborhood were limited to the forty-five stellar systems enclosed
by a 5.2 pc radius sphere. Reid & Gizis (1997) expand this volume to 8 pc, but restricted to
declinations greater than −30◦ . The most recent update to this “8 pc sample” finds 140 mainsequence stars, three brown dwarfs, and nine white dwarfs in 108 systems (Reid et al. 2004). The
project described in the following chapters adopts a distance limit of 20 pc in order to include a
sufficiently large number of brown dwarfs so that the sample can be used for statistical study.
Reid, Gizis, & Hawley (2002) have estimated the luminosity and mass function of the Solar
Neighborhood by combining spectroscopic observations of objects listed in the Third Catalog of
Nearby Stars (Gliese & Jahreiß 1991, pCNS3), the “PMSU” sample, with Hipparcos data (ESA
1997). The resulting PMSU sample consists of 548 main-sequence stars in 448 systems and, using
the Hipparcos data for bright, massive stars, they derive the luminosity function for main-sequence
stars with −1 < MV ≤ 17. (Because the multiplicity of the Hipparcos sample is somewhat lower
than the expected value, the contribution of multiple systems has been doubled.) The luminosity
function is shown in Figure 1.7. Notice the large Poisson error bars at low luminosities due to a
paucity of objects. The luminosity function is transformed to the mass function shown in Figure 1.8
using mass-MV calibrations. They find that, for 0.1 M¯ < M < 0.6 M¯ , their derived mass function
is consistent with a “flat” power-law distribution (Ψ(M ) = M −α ) with α ∼ 1.2.
Reid et al. (1999) used the first results from 2MASS (Kirkpatrick et al. 1999) to make the first
estimate of the luminosity and mass functions of very low-mass stars and brown dwarfs. Because
there is no mass-luminosity relation for brown dwarfs, they use Monte Carlo techniques and brown
dwarf evolutionary tracks to create model low-mass star and brown dwarf populations to compare
to the observed densities. They find 1 < α < 2 for M < 0.1 M¯ , with the more likely value being
α = 1.3. This result implies that brown dwarfs with M > 0.01 M¯ outnumber stars by almost a
factor of two, but only constitute one-sixth of the mass.
Burgasser (2002) used data for fourteen T dwarfs found in 14150 sq. deg. and significant
statistical analysis to derive the T dwarf luminosity function shown in Figure 1.9. Note that they
find the space density of T dwarfs to be increasing towards fainter magnitudes. They combine
this result with Monte Carlo simulations to constrain the substellar mass function to 0.5 < α < 1,
significantly shallower than the α ∼ 1.3 found by Reid et al. (1999).
The goal of the project described in the following chapters is to make a robust estimate of
the luminosity function for low-mass stars and brown dwarfs with spectral types ranging from M7
to L8—extending the work done by Reid, Gizis, & Hawley (2002) and greatly improving on the
estimate made by Reid et al. (1999). This is made possible through an extensive search for all of
the ultracool dwarfs out to 20 pc within the almost half of the sky covered by the 2MASS Second
Release. This project is described in great detail in Chapters 3 and 4. Finally, in Chapter 5, we
discuss the implications of this work and the work to be done in the future. First, however, the
following chapter describes our effort to use the 2MASS Second Release in combination with proper
motion catalogs to complete the census of nearby mid-to-late M dwarfs.
13
7
CaH
M1.5
6
TiO
M2.5
Normalized Flux + Constant
5
TiO
Na I
Hα
M4.5
4
KI
M5.5
TiO
3
M7
2
M8
CrH
1
VO
VO
FeH
M9
0
6000
6500
7000
7500
8000
Wavelength (Å)
8500
9000
Figure 1.1.— M dwarf spectral sequence with prominent spectral features labeled. The zero point
of each spectrum is shown with a dotted line.
14
11
10
9
Normalized Flux + Constant
8
7
6
5
4
3
2
1
0
6500
7000
7500
8000
8500
Wavelength (Å)
9000
9500
Figure 1.2.— L dwarf spectral sequence with prominent spectral features labeled. Even though these
are (publicly available) Keck data, several of the late-L spectra have a relatively low signal-to-noise
ratio. The zero point of each spectrum is shown with a dotted line.
15
Figure 1.3.— T dwarf spectral sequence with prominent spectral features labeled. The zero point of
each spectrum is shown with a dotted line. Reprinted by permission from Burgasser et al. (2004),
Figure 6.
16
Figure 1.4.— Near-infrared spectra of M and L dwarfs with prominent spectral features labeled. The
zero point of each spectrum is shown with a dotted line. Reprinted by permission from Burgasser
et al. (2004), Figure 1.
17
1.5
5
MJ
(J-H)
1.0
10
0.5
15
-0.5
0.0
0.0
0.5
1.0
(J−KS)
1.5
2.0
-0.2
0.0
0.2
0.4
(H-Ks)
0.6
0.8
1.0
Figure 1.5.— Near-infrared color-magnitude and color-color diagrams for late-type main sequence
stars (triangles), low-mass stars and warm brown dwarfs (M7–L8, circles), and cool brown dwarfs
(T0–T8, five-pointed stars).
18
3500
3000
2500
2000
1500
1000
500
-3
-2.5
-2
-1.5
-1
-.5
0
.5
1
Figure 1.6.— Effective temperature as a function of age for objects with a range of masses. The
contour interval is 0.005 M¯ for 0.02–0.1 M¯ and 1 MJ for 1–13 MJ . Adapted by permission from
Burrows et al. (2001), Figure 8.
19
Figure 1.7.— V -band luminosity function of nearby stars based on the 8 pc and Hipparcos 25 pc
samples. The contribution from known companions to the Hipparcos sample has been doubled to
account for missing binary components. Adapted by permission from Reid, Gizis, & Hawley (2002),
Figure 10.
20
-1
Hipparcos + PMSU
Single stars and primaries
Companions included
log ξ
-2
-3
-4
-5
-1
-0.5
0
log (M/M)
0.5
1
Figure 1.8.— Mass function estimate of the Solar Neighborhood. Adapted by permission from Reid,
Gizis, & Hawley (2002), Figure 12.
21
Figure 1.9.— Luminosity function of T dwarfs. The dashed-line histogram and the open data point
correspond to the assumption that the T dwarf 2MASS 0559 is single, while the solid line and points
assume that it is double. Reprinted by permission from Burgasser (2002), Figure 8.25.
22
23
Chapter 2
Meeting the Cool Neighbors. III.
Spectroscopy of Northern NLTT
Stars
This chapter is focused on the first spectroscopic results of our effort to uncover nearby late-type
stars in the Solar Neighborhood using the Luyten’s proper motion catalog (NLTT). We uncovered
many mid-to-late M dwarfs within 20 pc as part of this program. While these results are not directly
used to estimate the luminosity function of ultracool dwarfs, the stated goal of this dissertation,
this work represents my first experiences with the 2MASS data, optical spectroscopy, and spectral
typing—skills essential to the data analysis of future chapters.
There were several lessons learned as a result of this work. In particular, we initially used
spectral indices as a predictor of spectral type. However, for the spectral types of interest, the
diagnostics saturate and the indices become double valued (see Figure 2.3). It became clear that
the best way to spectral type was by side-by-side comparison to spectral standards. While this is
more laborious, the results are significantly more reliable and this method is used in future chapters.
In addition, we also initially used spectral indices to estimate MJ . This method relies on three
spectral indices and was fraught with complications. Thankfully, MJ has been shown to be very
well correlated with optical spectral type and, in all future work, we used this relation to estimate
absolute magnitudes as described in § 3.5.2.
This chapter is a reprinting of a paper, of which I am the primary author, published in The
Astronomical Journal and was written in collaboration with Neill Reid. I was responsible for creating
the sample, compiling the target lists for observing runs, and the data reduction and analysis. I also
derived the spectral type and MJ calibrations. Reid is responsible for the analysis and discussion of
the chromospheric activity of the sample.
24
2.1
Abstract
We present initial results of an all-sky search for late-type dwarfs within 20 pc of the Sun using
the New Luyten Two-Tenths (NLTT) catalog cross-referenced with the Two Micron All-Sky Survey
(2MASS) database. The results were obtained with low-resolution optical spectroscopic follow-up of
candidate nearby-stars as a preliminary test of our methodology. MJ , derived using spectral indices,
and 2MASS J are used to estimate distances. Out of the 70 objects observed, 28 are identified as
previously unrecognized objects within 25 pc of the Sun, and up to 19 of these are within 20 pc.
One, LP 647- 13 is an M9-type dwarf at 10.5 pc making it one of the four closest M9 dwarfs currently
known. We also discuss the chromospheric activity of the observed dwarfs.
2.2
Introduction
This is the third in a series of papers which present the results of our survey of the low-mass
residents of our immediate Solar Neighborhood. Reid & Cruz (2002, hereafter Paper I) discussed
how our capabilities for finding low-luminosity main-sequence stars has been enhanced with the
availability of the Two Micron All-Sky Survey (Skrutskie 2001, 2MASS). The method that we focus
on in this paper is using 2MASS in conjunction with proper-motion catalogs—particularly the New
Luyten Two-Tenths catalog (Luyten 1979, NLTT). This strategy is one part of a comprehensive
search for previously-unrecognized nearby stars. The goals of the project are two-fold: to identify
late-type dwarfs within 20 pc that can be targeted for detailed study as part of the NSF/NStars
project and to use this sample to determine the mass function of low-mass objects in the Galactic
Disk.
Our first results have come from targeting high proper-motion objects from the NLTT catalog.
As discussed in Paper I, we were able to identify a substantial fraction of the proper-motion stars in
the 2MASS database based on location coincidence. With this sample, we are able to select candidate
nearby dwarfs by combining the mr estimates from the NLTT and the near-infrared magnitudes
provided by 2MASS and using (mr − KS ) colors to obtain a rough photometric distance.
As detailed in Paper I, our initial sample of nearby-star candidates is drawn from NLTT objects
that have a 2MASS counterpart within a 1000 search radius. While 23,795 objects were found, only
1245 have photometric properties consistent with their being late-type dwarfs within 20 pc of the
Sun. This sample is dubbed NLTT Sample 1.
NLTT Sample 1 has already yielded many previously unrecognized nearby objects. In Paper I,
we combine the 2MASS infrared magnitudes with published optical photometry for 469 dwarfs,
identifying 76 additions to the 20 pc sample. Reid, Kilkenny, & Cruz (2002, hereafter Paper II)
lists 48 new objects within 20 pc, five of which are probably within 10 pc. These were located by
obtaining optical photometry of 180 bright southern nearby-star candidates with the facilities at the
Sutherland station of the South African Astronomical Observatory.
25
This paper presents the first results from spectroscopic follow-up observations of NLTT stars.
The selection of the current sample and its overlap with the finalized NLTT Sample 1 are outlined
in § 2.3. Section 2.4 describes our observations. We present spectral indices, spectral types, absolute
magnitudes, and distances for all the observed objects in § 2.5. A discussion of our findings, particularly interesting objects, and chromospheric activity is in § 2.6. We summarize the main results in
the final section.
2.3
Target Selection
The objects presented in this paper are taken from the initial sample of 23,795 NLTT objects
that have a 2MASS counterpart within 1000 of the NLTT position and |b| > 10◦ , but were selected
before we finalized the criteria for defining the NLTT Sample 1. Indeed, these observations provided
some of the basis for those criteria.
The present set of targets were required to have declinations greater than −30◦ and right
ascensions between 21h and 5h . The following color criteria further reduced the sample to 907
objects:
mr (lim)



 1.67(mr − Ks ) + 5.5,
=
5(mr − Ks ) − 4.5,


 1.72(m − K ) + 8,
r
s
if 1.5 < (mr − Ks ) ≤ 3,
(2.1)
if 3 < (mr − Ks ) ≤ 3.8,
if 3.8 < (mr − Ks ) ≤ 7.
Objects were eliminated if mr > mr (lim).
Primary and secondary target lists were created by invoking stricter color criteria, designed
to probe areas of color-space most likely to contain nearby, late-type objects. The primary list
includes 52 objects which meet the above criteria and have (J − KS ) colors redder than 0.95 and
(H − KS ) > 0.35. The (J − KS ) cut eliminated 628 objects while the (H − KS ) eliminated 818.
The secondary list includes 119 targets, all with (R − KS ) > 5. Taking into account the significant
overlap between the two lists, there is a total of 127 target objects. Twenty-nine already have
spectroscopic observations, with most identified as mid to late M-dwarfs (Table 2.1). Twenty-eight
objects were eliminated because the 2MASS magnitudes were unreliable due to nearby bright stars
or their diffraction spikes, unresolved companions, or an NLTT/2MASS mismatch. A mismatch
occurs when more than one 2MASS object is within 1000 of the NLTT position and the NLTT object
is linked with both the correct and incorrect 2MASS objects (see Paper I, §3.3). In some cases, we
were able to correct the mismatches and observe the appropriate object. The resulting target list
includes 70 objects — all of which we observed and present here1 .
Following this initial observing run, we were able to refine our color criteria to more efficiently
exclude objects beyond 20 pc. The finalized criteria are described in Paper I and were used to create
1 Finder
charts can be obtained from the 2MASS Survey Visualization and
http://irsa.ipac.caltech.edu/ using the positions or names given in Tables 2.2 and 2.3.
26
Image
Server
at
the NLTT Sample 1 consisting of 1245 targets. These observations include a significant number of
targets lying beyond the 20 parsec limit. In Figure 2.1, we show all of the observed objects with
the finalized (mr , R − Ks ) color criteria superimposed (see Paper I, §3.2). Objects in the NLTT
Sample 1 are listed in Table 2.2, while data for targets which fail to meet our final selection cut are
presented in Table 2.3.
2.4
Observations
We obtained optical spectroscopy of our sample with the Kitt Peak National Observatory 2.1-m
telescope using the GoldCam CCD Spectrograph. We employed a 400 line mm−1 grating blazed at
8000 Å with a 1.00 3 slit to give a resolution of 5.1 Å (2.8 pixels) over the wavelength range 5500–
9300 Å. We used an OG-550 blocking filter to block higher orders. The observations were taken
over four nights from 2000 September 29 through October 2 (UT), all under photometric conditions
and with good seeing (between 100 and 1.00 5).
The spectra were extracted and wavelength and flux calibrated using standard IRAF routines.
We used zero-second dark exposures taken at the beginning of each night to remove the bias level
from each exposure, via the IRAF routine CCDPROC, which was also used to fix bad pixels. All
spectra were extracted using APALL. Wavelength calibration was determined from HeNeAr arcs
taken after each exposure. The spectra were flux calibrated using observations of HD 19445 (Oke &
Gunn 1983), and the spectral ratios were measured using IDL scripts.
The CCD used with GoldCam suffers from fringing in the red which has an amplitude of ±3%
at 8000 Å, rising to ±10% at 8400 Å. In an attempt to compensate for this effect, an internal-lamp
flat-field exposure was taken after each stellar observation. However, we were unable to use these
data to correct the observed fringing in a satisfactory manner. Since the fringing does not affect
the spectrum in the regions sampled by the measured bandstrength indices, and since there are no
significant flat-field features shortward of 7800 Å, we have not applied flat-field corrections to the
data.
2.5
Results
The change in strength of the major features present in spectra of late-type stars is tied to
variation in effective temperature. Thus, we use measurements of the strengths of those features
to estimate spectral type and absolute magnitude. Band strengths can be quantified by measuring
spectral ratios or indices. Table 2.4 defines the spectral indices used in our study. These are taken
from Reid, Hawley, & Gizis (1995, hereafter PMSU1), Kirkpatrick et al. (1999), and Martı́n et al.
(1999), and are designed to measure the strengths of the most prominent features of M and early Ltype dwarfs. The indices are calculated by taking the ratio between the summed flux in a region that
27
contains an atomic or molecular feature and the summed flux in a nearby region that approximates
the local pseudo-continuum. Table 2.5 lists the measurements for all of the observed objects.
2.5.1
Metallicity
In late-type dwarfs the relative strength of CaH and TiO absorption provides a metallicity indicator, with TiO absorption decreasing more rapidly than CaH with decreasing metal abundance
(Mould 1976). Gizis (1997) used this behavior to define a classification system for late-type subdwarfs, classifying stars as either subdwarfs, sdM (intermediate abundance, [Fe/H]∼ −1), or extreme
subdwarfs, esdM ([Fe/H] < −1.5). Figure 2.2 plots the CaH 1-TiO 5 and CaH 2-TiO 5 diagrams for
our sample, where data for the reference stars are taken from PMSU1 (the disk main sequence) and
Gizis (1997, sdM and esdM sequences). All of our targets, except LP 410-38 (2M 0230) and LP 7021 (2M 2310), have spectral indices consistent with their being near solar-abundance disk dwarfs.
These two objects are further discussed in §2.6.2. While the location of LP 824-383 (2M 0012) in
the CaH 2-TiO 5 plane is consistent with that of an intermediate subdwarf, the spectrum has a low
signal-to-noise ratio and the CaH 1 and CaH 2 measurements are not reliable.
2.5.1.1
Spectral Types
We have defined the spectral type calibration using data for nearby stars and brown dwarfs
with published spectral types (Kirkpatrick et al. (2000); PMSU1). We have supplemented our
own observations with Keck Low-Resolution Infrared Spectrometer (Oke et al. 1995, LRIS) spectra
of late-M and L dwarfs obtained by I. N. R and collaborators as part of the 2MASS Rare Object
Project2 . Spectral ratios for the standards were measured using the same scripts used for the KPNO
data presented here. The indices that best correlate with spectral type are TiO 5 and VO-a. Both
indices are double-valued, with TiO 5 reversing in strength at M7 and VO-a at M9. For the early
TiO 5 sequence, we adopt the relation found by PMSU1. The data and the calibration curves are
plotted in Figure 2.3.
The spectral type calibration relations are:
Sp = −10.775(TiO 5) + 8.200,
Sp = 5.673(TiO 5) + 6.221,
(TiO 5) ≤ 0.75,
(TiO 5) ≥ 0.3,
σ = 0.5 subclasses,
σ = 0.38 subclasses, 23 stars,
Sp = 10.511(VO-a) − 16.272,
σ = 0.82 subclasses, 59 stars,
Sp = −7.037(VO-a) + 26.737,
σ = 0.50 subclasses, 22 stars.
In principle, these relations yield up to four estimates of the spectral type. However, the fact that
the two indices’ trends reverse at different spectral types allows us to resolve the ambiguity since
2 Most
of the spectra are publicly available from http://dept.physics.upenn.edu/∼ inr/
28
only one pair of solutions agree. We take the spectral type to be the weighted average of the results
(one from TiO 5 and one from VO-a) rounded to the nearest half spectral type. The resulting
uncertainty is ±0.5 subclasses.
2.5.2
Absolute Magnitudes and Derived Distances
The absolute magnitude/band strength calibration was defined using a sample of 68 late-type
dwarfs (from K5 to M7) with well-determined trigonometric parallaxes, taken from the nearby stars
surveyed by PMSU1. The latter authors provide band strength measurements for a variety of
indices. We find that color-magnitude diagrams using the TiO 5, CaH 2, and CaOH indices show
The uncertainty in MJ was calculated by adding in quadrature two contributions to the uncertainty: the RMS of the weighted average based on the RMS of the individual calibration fits stated
above and the standard deviation of the values of MJ given by the different spectral ratios. Using
this scheme and the 2MASS apparent J magnitude, we estimate MJ and the distance to all of our
(disk dwarf) targets (Tables 2.2 and 2.3).
2.6
Discussion
2.6.1
Additions to the Nearby-Star Sample
Our spectroscopic observations confirm that combining optical and near-infrared photometry
is an effective means of identifying new stellar neighbors, even when the optical photometry is as
unreliable as the magnitudes listed in the NLTT catalog. In particular, of the 35 stars listed in
Table 2.2, selected on the basis of our finalized color-magnitude criteria, up to 19 (54%) are likely
to lie within 20 pc of the Sun, while up to 27 (77%) probably lie within the 25 pc sample. Several
stars require particular comment.
2.6.1.1
LP 647-13
At spectral type M9, LP 647-13 (2M0109) is the latest of the NLTT dwarfs in the present sample,
falling beyond the range of validity of the absolute magnitude calibrations plotted in Figure 2.4.
Figure 2.5 compares our spectrum of this object with Keck LRIS data for the M9 standard LHS 2065
and the M9.5 standard BRI 0021-0214. There are obvious strong similarities between LP 647-13 and
LHS 2065. Kirkpatrick, Henry, & Simons (1995) list absolute magnitudes for these two standard
stars and for two other M9 dwarfs in the immediate Solar Neighborhood: MK = 10.33 for LHS 2065;
MK = 10.22 for BRI 0021; MK = 10.46 for LHS 2924; and MK = 10.24 for TVLM 868-110638.
A straight average gives MK = 10.31 ± 0.11 magnitudes. Applying that value gives a distance of
only 10.5 pc to LP 647-13, making it one of the four closest M9 dwarfs currently known, along with
LHS 2065 at 8.5 pc, LHS 2924 at 10.5 pc, and DENIS-P J104814.7−395606.1 at ∼5 pc (Delfosse et
al. 2001).
2.6.1.2
LP 763-38
This dwarf (2M2337) has spectral indices which place it at the extreme limit of validity of our
calibration. Figure 2.6 plots our spectral data and compares those with the M7 standard, VB 8
(Gl 644C). Given the strong similarities, we classify LP 763-38 as spectral type M7, and estimate
the distance using VB 8 (MK =9.76) as a template. Matching that value against the observed K
magnitude of 11.206 for LP 763-38 gives a distance modulus of 1.47 magnitudes, or a distance
estimate of 20.0 ± 3.0 pc.
30
2.6.2
Possible Subdwarfs: LP 410-38 & LP 702-1
As discussed above, our band-strength measurements suggest that these two stars (2M0230 and
2M2310, in Table 3) are intermediate-abundance subdwarfs. Figure 2.7 compares our spectra against
data for LP 890-2 (2M0413, Table 2), an M6 dwarf in our NLTT sample, and LHS 377, one of the
coolest-known intermediate subdwarf (sdM7, Gizis (1997)). LP 702-1 is clearly similar to LP 890-2,
suggesting that the subdwarf-like spectral indices may reflect the relatively low signal-to-noise ratio
of our spectrum. LP 410-38, on the other hand, has spectral characteristics which are closer to
LHS 377, notably the enhanced CaH absorption at 6400 and 7000 Å. We therefore classify LP 702-1
as an M6, near-solar abundance disk dwarf, but identify LP 410-38 as an intermediate subdwarf,
spectral type sdM6. We adopt MJ = 10.15 ± 0.16 for LP 702-1. This was computed by averaging
the values of MJ for all of the M6-type dwarfs in our sample. This yields a distance estimate of
37.0 ± 5.0 pc. The Gizis (1997) subdwarf sample does not include any sdM6 stars, but both LHS 377
and LHS 407 (sdM5) have measured parallaxes (Monet et al. (1992) and Ruiz & Anguita (1993),
respectively). Ruiz & Anguita (1993) also present JHK photometry for LHS 407, while Leggett et
al. (2000) list such data for LHS 377. Combining those measurements gives MK = 9.74 ± 0.4 for
LHS 377 and MK = 9.55 ± 0.8 for LHS 407. We therefore adopt MK = 9.7 for LP 410-38, giving a
distance estimate of 18.0 ± 5.0 pc. We note that the Hα emission evident in LP 410-38 is unusual,
but not unprecedented, in late-type subdwarfs, and might reflect the presence of a close companion,
as with Gl 455 and Gl 781 (Gizis 1997).
2.6.3
Chromospheric Activity
Chromospheric activity, as evidenced by emission at either the Ca II H & K lines or the Balmer
series, is common among late-type dwarfs. A significant number of the NLTT dwarfs exhibit Hα
emission, as evidenced by Hα indices exceeding 1.0 in Table 2.5. We have used the options available
in the IRAF routine SPLOT to measure equivalent widths and line fluxes for 43 stars, and the
results are listed in Table 2.6. Our observations set a typical upper limit of 0.75 Å on Hα emission
in the remaining stars. This fraction of ∼ 60% is broadly consistent with the expected proportion
of dMe dwarfs at spectral types of M5 to M6 (see Figure 6 in Gizis et al. (2000)).
Equivalent width is still often used to characterize the level of activity but, as pointed out
originally by Reid, Hawley, & Mateo (1995) and later by Basri & Marcy (1995), this approach fails
to take into account the decreased continuum level in later-type stars. A more effective means of
gauging the relative activity of dwarfs spanning a wide range of spectral types (temperatures) is to
consider the fraction of the total flux emitted as line emission, specifically Fα /Fbol , where Fα is the
total flux in the Hα line.
Our spectra give a direct measure of Fα . In order to determine Fbol , we need to estimate
bolometric corrections for the NLTT dwarfs. We can calculate the latter using data from Leggett et
al. (2000) observations of 28 nearby M dwarfs with spectral types between M1 and M6.5. Figure 2.8
31
plots the J-band bolometric corrections for those stars as a function of both spectral type and TiO 5
index, taking the latter from PMSU1. Both correlations are well described by linear relations
BCJ = (1.658 ± 0.021) + (0.050 ± 0.005) × sp. type,
σ = 0.036,
and
BCJ = (2.065 ± 0.020) − (0.533 ± 0.050) × TiO 5,
σ = 0.037.
We have used the latter relation to estimate bolometric corrections for the NLTT dwarfs with
spectral types M1 to M6.5; we adopt BCJ =1.9 magnitudes for later spectral types (Reid et al.
2001). Table 2.6 lists the resulting values of log Fα /Fbol for dwarfs with measurable Hα emission.
Figure 2.9 compares the distribution of activity amongst the present sample against data for
nearby emission-line M dwarfs from Hawley, Gizis, & Reid (1996, hereafter PMSU2). 2M0203
(LP 352-79) stands out as the most active star in the sample, with log Fα /Fbol = − 3.21. We also
note that Gizis et al. (2000) failed to detect Hα emission in the M9 dwarf, 2M0350+1818, while
we measure an Hα equivalent width of 13.3 Å. Previous observations have shown that moderatestrength flares tend to occur with a duty cycle of a few percent amongst ultracool (spectral types
later than M6.5) dwarfs (Reid et al. 1999; Martı́n & Ardila 2001), and this mechanism probably
accounts for the relatively high levels of activity in both these dwarfs.
Considering the overall distribution in Figure 2.9, the (mainly) M5/M6 dwarfs observed in
this paper are clearly less active, on average, than the dMe dwarfs in the PMSU sample. This
is not unexpected, since recent studies indicate that the average level of activity is significantly
lower amongst chromospherically-active ultracool dwarfs (Gizis et al. 2000; Basri 2001). Indeed, our
observations bridge the gap between the ultracool datasets and the PMSU stars, which include few
dwarfs between spectral types M5 and M7. Our data show that the average level of activity amongst
dMe dwarfs falls from hlog Fα /Fbol i = −3.9 at spectral types earlier than M5 to hlog Fα /Fbol i ∼
−4.25 for M5.5 dwarfs. Activity declines even further at later types, with hlog Fα /Fbol i ∼ −5 at
spectral type M9 and only 10 to 20% of early-type L dwarfs having detectable Hα emission.
2.7
Summary
We have presented spectroscopic observations of 70 late-type dwarfs selected from the NLTT
proper motion catalog as probable members of the immediate Solar Neighborhood based on their
optical/near-infrared photometric properties. Of these 70 objects, 28 are found to be previously
unrecognized stars within 25 pc of the Sun; 13 lie within 20 pc.
In addition to identifying a small sample of new members of the local stellar community, the
observations described in this paper lay the foundations for the analysis of future observations. We
have identified and calibrated a number of narrowband spectral indices which can be used to determine spectrophotometric parallaxes and spectral types for M dwarfs. Based on those calibrations,
32
we have refined the photometric selection criteria used to identify candidate nearby stars from our
cross-referencing of the NLTT catalog against the 2MASS database. Future papers will apply the
techniques outlined in this paper to spectroscopic observations of a larger sample of nearby-star
candidates.
33
13
14
15
mr
16
17
18
19
20
4
5
6
7
8
9
(mr – Ks)
Figure 2.1.— Our 70 objects in the (mr , mr − Ks ) plane. Circles are objects that are included in
NLTT Sample 1 described in Paper I. Squares are not in the finalized sample. The dashed line
marks the limits, mr (lim), for NLTT Sample 1.
34
1.3
1.3
1.1
1.1
0.9
0.9
CaH 2
CaH 1
LP 824-383
0.7
LP 702-1
0.7
LP 410-38
0.5
0.5
0.3
0.3
LP 702-1
LP 824-383
LP 410-38
0.1
0.1
0.0 0.2 0.4 0.6 0.8 1.0 1.2
0.0 0.2 0.4 0.6 0.8 1.0 1.2
TiO 5
TiO 5
Figure 2.2.— Comparison between the CaH and TiO 5 band-strengths measured from our observations of NLTT dwarfs and standard stars. The green plus signs mark data for disk dwarfs from
PMSU1; open red squares are sdM subdwarfs and blue crosses are esdM subdwarfs from Gizis (1997);
our observations are plotted as solid black circles. Three possible M subdwarfs are identified. As
discussed in the text (§§2.5.1 and 2.6.2), both LP 824-383 and LP 702-1 have low signal-to-noise
spectra and are probably not metal poor.
35
Spectral Type
L4
L4
L2
L2
L0
L0
M8
M8
M6
M6
M4
M4
M2
M2
M0
1.5
1.3
1.1
0.9
0.7
0.5
2.4
0.3
TiO 5
2.2
2.0
M0
1.8
VO-a
Figure 2.3.— TiO 5 and VO-a spectral type calibrations. Late-type calibrating objects (later than
M7 for TiO 5 and M9 for VO-a) are plotted as open circles, earlier types as open squares, and our
standards as solid triangles. The dotted line illustrates the separation of the two trends. Data are
from PMSU1 and Kirkpatrick et al. (2000). In addition, our standards were included in calculating
the late-type TiO 5 and early-type VO-a relations. The early TiO 5 relation was adopted from
PMSU1 and our standards are overplotted to show their agreement.
36
MJ
5
5
6
6
7
7
8
8
9
9
10
10
11
11
VB10
12
BRI 0021-0214
BRI 0021-0214
TVLM 513-42404a
12
TVLM 513-42404a
13
13
TVLM 513-42404b
14
0.9
TVLM 513-42404b
14
0.8
0.7
0.6
0.5
TiO 5
0.4
0.3
0.2
0.8
0.7
0.6
0.5
CaH 2
0.4
0.3
0.2
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
CaOH
Figure 2.4.— Absolute magnitude calibration using K7 and later dwarfs. Circles are the data
included in the calibration for brighter objects while the fainter calibration objects are plotted
as squares. The dashed boxed regions (0.34 ≤ TiO 5 ≤ 0.43, 0.36 ≤ CaH 2 ≤ 0.42,
0.36 ≤ CaOH ≤ 0.43) show where the calibration is double-valued. The crosses, VB 10 (M8),
TVLM 513-42404a (M7), TVLM 513-42404b (M9), and BRI 0021-0214 (M9.5), show that the trends
reverse for later types.
37
1
0.8
BRI0021
0.6
LP 647-13
0.4
0.2
LHS 2065
0
6500
7000
7500
8000
8500
Wavelength
Figure 2.5.— Spectrum of LP 647-13, an M9 dwarf at 10.5 pc. Keck LRIS spectra of the M9 and
M9.5 standards, LHS 2065 and BRI 0021-0214, are shown for comparison.
38
1
0.8
LP 763-3
0.6
0.4
VB 8
0.2
0
6500
7000
7500
8000
8500
Wavelength
Figure 2.6.— Spectrum of the M7 dwarf, LP 763-3. The spectrum of the M7 standard, VB 8, is
shown for comparison.
39
Figure 2.7.— A comparison between our spectra of the two subdwarf candidates, LP 702-1 and
LP 410-38, and data for an M6 dwarf (LP 890-2) and the late-type intermediate subdwarf, LHS 377
(a Keck LRIS spectrum). As discussed in the text, while LP 702-1 is probably misclassified due to the
relatively low signal-to-noise ratio, LP 410-38 shows the enhanced hydride absorption characteristic
of mildly metal-poor subdwarfs.
40
2.2
BCJ
2.0
1.8
1.6
M0
M2
M4
M6
Spectral type
2.2
BCJ
2.0
1.8
1.6
1.0
0.8
0.6
0.4
0.2
0
TiO 5
Figure 2.8.— J-band bolometric correction as a function of spectral type and TiO 5 index for M0
to M7 dwarfs based on data from Leggett et al. (2000).
41
-3.0
log(Fα / Fbol)
-3.5
-4.0
-4.5
-5.0
-5.5
8
12
10
14
Mbol
-3.0
log(Fα / Fbol)
-3.5
-4.0
-4.5
-5.0
-5.5
K5
M0
M5
L0
Spectral type
Figure 2.9.— Distribution of chromospheric activity amongst the NLTT M dwarf sample, plotted
against Mbol (top) and spectral type (bottom). Data for nearby dMe stars from the PMSU2 sample
(crosses); NLTT dwarfs with detected Hα emission in the present sample (circles); upper limits for
the remaining NLTT dwarfs (triangles) are shown.
42
43
759759699759760460345-
17
25
43d
82
3
44
18
292- 67
349- 25
766- 87a
BD+22 176Bb
768- 26
768- 27
468-199a
30- 55
469-118c
245- 10
245- 18
411- 6
412- 31
356-770
413- 53
593- 68
LP/NLTT
Name
BRI 2202-1119
LHS 3762
Gl 852A
LHS 523
LHS 1604
GJ 1072
LHS 1378
G 074-015
LHS 1443
LHS 1146
GL 53.1B
GL 65B
GL 65A
LHS 1294
G 245-040
LHS 112
Other
Name
00
00
00
01
01
01
01
02
02
02
02
02
03
03
03
03
04
22
22
22
22
22
22
22
20
27
46
07
39
39
45
01
08
17
20
46
20
30
50
51
50
02
05
08
17
28
35
55
29.22
55.91
20.44
38.52
01.21
01.21
45.29
54.02
12.22
09.93
25.24
34.85
59.65
05.07
57.37
00.03
50.83
11.26
35.76
39.06
18.99
54.40
49.07
58.45
α
(J2000)
33
22
−19
22
−17
−17
13
73
15
35
37
16
18
24
18
00
22
−11
−11
−08
−08
−13
18
28
05
19
24
57
57
57
06
32
08
26
47
25
54
05
18
52
07
09
04
14
48
25
40
22
δ
08.28
32.89
43.95
21.91
02.62
02.62
00.39
32.13
43.23
33.03
30.68
11.44
23.26
28.25
06.54
44.11
22.49
45.98
28.71
33.37
12.08
17.86
29.93
46.65
15.57
···
···
12.01
15.60
15.47
···
13.87
13.37
15.88
10.92
15.98
···
···
···
17.19
14.48
···
···
···
13.31
16.96
···
···
MV
2
6
6
6
2
4
2
2
6
12
6
6
2
RefV
9.81 ± 0.10
10.99 ± 0.36
10.30 ± 0.17
7.90 ± 0.05
9.21 ± 0.03
9.21 ± 0.03
6.65 ± 0.16
9.11 ± 0.68
···
9.88 ± 0.02
7.30 ± 0.68
10.09 ± 0.22
11.39 ± 0.35
10.83 ± 0.36
11.45 ± 0.36
10.43 ± 0.06
9.12 ± 0.05
···
9.81 ± 0.31
9.98 ± 0.20
8.93 ± 0.13
10.60 ± 0.12
11.25 ± 0.36
···
MJ
15.2
17.0
18.2
···
12.2
12.7
18.0
14.1
14.4
14.7
17.0
16.1
17.6
18.1
19.2
16.5
14.7
17.8
16.7
17.9
14.0
16.1
17.9
17.3
mr
10.312
10.608
12.694
9.494
6.302
6.302
12.783
9.252
···
9.965
8.954
10.971
11.744
12.357
12.951
11.262
9.863
12.364
11.682
12.645
9.010
10.780
12.458
12.554
J
9.734
9.970
12.094
8.899
5.685
5.685
12.088
8.669
···
9.355
8.312
10.518
11.043
11.745
12.222
10.592
9.339
11.714
11.060
12.099
8.463
10.231
11.826
11.935
H
9.347
9.561
11.711
8.693
5.358
5.358
11.755
8.382
···
8.974
8.098
10.159
10.572
11.361
11.763
10.191
8.998
11.357
10.726
11.730
8.173
9.846
11.333
11.538
Ks
12.6 ± 0.6
8.5 ± 1.4
30.2 ± 2.3
20.8 ± 0.5
2.62 ± 0.04
2.62 ± 0.04
168.9 ± 12.2
11.2 ± 3.4
···
10.4 ± 0.1
22.5 ± 6.8
15.1 ± 1.5
11.9 ± 1.9
20.5 ± 3.4
20.2 ± 3.3
14.7 ± 0.4
14.1 ± 0.3
···
23.9 ± 3.4
34.2 ± 3.2
10.4 ± 0.6
10.9 ± 0.6
17.7 ± 2.9
···
d
(pc)
Table 2.1. Previously Known Objects in Our Sample of NLTT Targets
7
8
8
7
6
9
8
5
7
7
1
Refπ
3
10
4, 11
3
3
2
4
2
3
4
Refph
M5.5
M8.0
M6.0
M3.0
M5.5
M5.5
M1.5
M4.5
M4.5
M5.0
M2.5
M6.0
M9.0
M7.0
M9.0
M6.0
M5.0
M6.5
···
M5.0
M4.0
M6.5
M7.0
M6.0
Sp.
Type
4
2
6
3
3
2
3
4
6
6
6
4
2
4
2
2
6
3
3
3
2
2
3
Refsp
44
43.93
55.00
48.99
29.03
21
44
12
27
53
10
24
02
38.67
40.80
38.76
05.71
···
14.78
···
···
MV
2
RefV
11.01 ± 0.36
9.40 ± 0.01
11.01 ± 0.36
···
MJ
18.1
12.7
18.4
17.7
mr
12.761
6.90
12.615
12.759
J
12.101
6.252
11.952
12.078
H
11.708
5.934
11.562
11.699
Ks
22.7 ± 3.7
3.17 ± 0.02
21.2 ± 3.5
···
d
(pc)
7
Refπ
3
3
Refph
M7.0
M5.0
M8.0
M6.0
Sp.
Type
3
2
3
3
Refsp
References. — (1) Harrington et al. (1985); (2) PMSU1; (3) Gizis et al. (2000); (4) Luyten (1979); (5) ESA (1997); (6) Gliese
& Jahreiß (1991); (7) Harrington & Dahn (1980); (8) Monet et al. (1992); (9) Dahn et al. (2002); (10) Tinney, Mould, & Reid
(1993); (11) Reid (1993); (12) Weis (1991).
Note. — Column 1 lists the designation from the NLTT catalog. Identifiers without prefixes are Luyten-Palomar (LP)
Survey numbers. Other identifiers are R=Ross and BD=Bonner Durchmusterung. Column 2 lists alternate designations.
Columns 3 and 4 list the position of the 2MASS source. Column 5 lists MV and Column 6 gives the source. Column 7
gives the value of MJ obtained using our distance estimates. Column 8 lists the mr given in the NLTT. Columns 9-11 list
the infrared photometry from 2MASS. Column 12 lists the distance estimates, and Column 13 and 14 give the source of
the trigonometric parallax or photometry upon which the distance estimate is based. Column 15 lists the spectral type and
Column 16 gives the source.
Used TiO 5 and CaH 2 indices and our calibrations to find MJ and a distance estimate. Final estimate is average of this
value with estimates based on optical photometry
d
The system made up of two NLTT objects, LP 469-118 and its close companion G 035-027, are unresolved by 2MASS and
the photometry is not reliable.
c
Distance based on trigonometric parallax for companion, GL 53.1A
36
41
49
58
δ
b
23
23
23
23
α
(J2000)
Used TiO 5 and CaH 2 indices and our calibrations to find MJ and distance.
Gl 905
Other
Name
a
402- 58
R 248
523- 55
348- 11
LP/NLTT
Name
Table 2.1 (cont’d)
45
397817698638288521401-
10
54
2
50
40
18
10
31-302d
714- 37
890- 2f
775- 31
415-302
655- 48
716- 10
396- 18
651- 17
299- 15
888- 18
247- 56
31-301d
405- 5
645- 53
647- 13
467- 17
768-113
352- 79
649- 72
649- 93
NLTT/LP
Name
LHS 3856
LHS 1690
1RXS
G 221-27
LHS 1450
G 75-35
LHS 1363
G 272-43
LHS 1060
Other
Name
21
21
21
21
22
22
22
04
04
04
04
04
04
04
21
02
03
03
03
04
00
00
01
01
01
02
02
02
02
16
29
32
51
36
48
54
05
10
13
35
39
40
52
02
50
05
31
38
05
21
35
09
12
33
03
14
18
41
06.29
23.39
29.74
27.01
01.58
22.45
11.11
56.50
48.10
39.81
16.14
31.60
23.27
04.01
47.01
02.39
07.86
30.26
18.63
57.40
16.44
44.13
51.17
00.03
58.01
28.65
12.51
57.89
15.11
α
(J2000)
22
−18
−05
−01
36
12
25
71
−12
−27
−16
16
−05
−10
22
−08
27
−30
38
71
18
−05
−03
15
−17
21
−03
−06
−04
38
55
11
27
55
32
27
16
51
04
06
15
30
58
37
08
42
42
28
16
43
41
43
02
38
34
57
17
32
δ
46.28
07.48
58.62
14.32
51.34
10.54
56.48
38.55
42.17
29.14
57.52
44.85
08.29
21.87
12.05
41.88
27.94
38.19
56.03
41.00
56.02
10.20
26.41
17.20
23.63
16.95
43.35
49.73
17.75
17.3
15.9
16.6
16.2
18.2
15.9
16.5
15.1
15.1
18.4
17.4
15.0
16.4
15.5
16.1
16.5
16.3
18.2
17.0
13.9
15.7
14.9
17.9
16.9
13.7
16.7
15.5
19.2
14.2
mr
J
11.787
11.271
11.439
11.309
12.155
11.206
11.629
10.125
11.060
12.214
10.396
10.120
10.681
10.488
11.119
11.878
11.602
11.371
11.962
9.542
11.290
10.656
10.715
10.746
11.552
10.627
11.030
9.547
10.469
11.578
9.780
9.539
9.985
9.956
10.582
11.226
11.023
10.699
11.338
8.983
10.758
10.084
10.921
11.321
8.268
11.027
9.839
12.186
8.566
H
10.815
10.288
10.385
10.380
11.286
10.226
10.695
9.234
10.015
11.190
9.336
9.187
9.557
9.612
10.342
10.850
10.636
10.276
11.003
8.716
10.400
9.716
10.418
10.965
8.003
10.700
9.466
11.860
8.269
Ks
9.86 ± 0.19
9.65 ± 0.19
···
9.89 ± 0.19
7.63 ± 0.35
9.72 ± 0.19
9.96 ± 0.19
10.19 ± 0.19
8.99 ± 0.19
7.94 ± 0.35
9.96 ± 0.19
9.55 ± 0.19
10.21 ± 0.19
9.79 ± 0.19
8.88 ± 0.19
7.86 ± 0.35
9.66 ± 0.19
9.90 ± 0.19
10.13 ± 0.19
10.26 ± 0.19
9.86 ± 0.19
10.00 ± 0.19
9.95 ± 0.19
9.08 ± 0.19
8.01 ± 0.35
10.10 ± 0.19
9.64 ± 0.19
9.86 ± 0.19
9.82 ± 0.19
9.44 ± 0.19
9.81 ± 0.19
9.90 ± 0.19
MJ (TiO 5)
9.47 ± 0.19
9.07 ± 0.19a
···
9.27 ± 0.19
7.55 ± 0.33
9.57 ± 0.19
9.57 ± 0.19
9.71 ± 0.19
8.82 ± 0.19
7.89 ± 0.33
9.54 ± 0.19
9.41 ± 0.19
9.86 ± 0.19
9.44 ± 0.19
8.55 ± 0.19
7.66 ± 0.33
9.58 ± 0.19
9.45 ± 0.19
9.92 ± 0.19
10.18 ± 0.19
9.51 ± 0.19
9.85 ± 0.19
9.40 ± 0.19
8.53 ± 0.19
7.64 ± 0.33
9.81 ± 0.19
9.39 ± 0.19
9.42 ± 0.19
9.64 ± 0.19
9.10 ± 0.19a
9.54 ± 0.19
9.81 ± 0.19
MJ (CaH 2)
9.68 ± 0.28
9.39 ± 0.28
···
9.37 ± 0.28
7.80 ± 0.32a
9.01 ± 0.28a
9.52 ± 0.28
7.66 ± 0.32c
9.08 ± 0.28
8.14 ± 0.32
9.66 ± 0.28
9.15 ± 0.28a
6.82 ± 0.32c
9.43 ± 0.28
8.71 ± 0.28
7.76 ± 0.32
9.67 ± 0.28
9.46 ± 0.28
9.63 ± 0.28
9.78 ± 0.28
9.67 ± 0.28
9.19 ± 0.28
9.93 ± 0.28
8.76 ± 0.28
7.81 ± 0.32
9.57 ± 0.28
9.52 ± 0.28
9.33 ± 0.28
9.61 ± 0.28
9.43 ± 0.28
9.42 ± 0.28
9.23 ± 0.28
MJ (CaOH)
Data for Targets Included in NLTT Sample 1
11.352
10.717
11.695
11.928
8.876
11.634
10.472
12.920
9.181
Table 2.2.
9.67 ± 0.20
9.37 ± 0.27
···
9.54 ± 0.30
7.67 ± 0.22
9.52 ± 0.33
9.72 ± 0.23
9.95 ± 0.28
8.94 ± 0.16
8.00 ± 0.22
9.73 ± 0.22
9.42 ± 0.20
10.03 ± 0.22
9.58 ± 0.21
8.72 ± 0.18
7.76 ± 0.21
9.63 ± 0.13
9.63 ± 0.24
9.95 ± 0.24
10.14 ± 0.24
9.68 ± 0.19
9.79 ± 0.37
9.72 ± 0.28
8.79 ± 0.26
7.81 ± 0.24
9.88 ± 0.25
9.51 ± 0.16
9.58 ± 0.26
9.71 ± 0.15
9.30 ± 0.20
9.63 ± 0.20
9.74 ± 0.32
MJ
21.8 ± 2.0
18.8 ± 2.3
10.5 ± 3.0e
30.3 ± 4.1
17.5 ± 1.8
26.7 ± 4.0
14.2 ± 1.5
39.6 ± 5.0
11.2 ± 0.8
17.3 ± 1.8
27.0 ± 2.7
27.4 ± 2.6
18.6 ± 1.9
30.0 ± 2.9
14.7 ± 1.2
22.9 ± 2.2
12.6 ± 0.7
19.4 ± 2.1
28.5 ± 3.1
11.3 ± 1.3
12.3 ± 1.1
15.3 ± 2.6
14.3 ± 1.8
29.4 ± 3.5
46.2 ± 5.1
24.2 ± 2.8
22.5 ± 1.6
23.7 ± 2.8
21.0 ± 1.5
37.4 ± 3.4
20.8 ± 1.9
24.2 ± 3.5
dph
(pc)
M5.5
M5.0
M5.5
M5.0
M4.5
M5.5
M5.5
M5.0
M5.5
M6.0
M6.0
M5.0
M6.0
M5.5
M4.5
M5.5
M5.0
M6.0
M5.0
M4.0
M5.0
M5.0
M9.0
M5.5
M3.5
M5.0
M5.5
M6.0
M4.0
Sp.
Type
N
N
N
?
N
?
N
Y
Y
N
Y
Y
Y
Y
N
N
N
Y
N
Y
?
Y
Y
N
Y
N
Y
N
Y
20
pc?
46
59
33
90
38
3
52
G 275-42
Other
Name
23
23
23
23
23
23
01
22
23
37
37
47
50.86
23.63
36.58
14.93
38.31
20.64
α
(J2000)
−05
−27
−22
−08
−12
42
39
25
32
38
50
38
δ
55.50
44.46
15.87
08.16
27.60
08.19
17.5
16.4
15.3
18.0
16.7
16.2
mr
11.312
11.594
11.039
12.246
11.461
10.942
J
10.691
11.053
10.441
11.603
10.851
10.353
H
10.415
10.752
9.960
11.206
10.427
10.094
Ks
MJ (CaH 2)
7.38 ± 0.33
9.71 ± 0.19
7.14 ± 0.33
···
9.74 ± 0.19
9.15 ± 0.19a
MJ (TiO 5)
7.71 ± 0.35a
9.90 ± 0.19
7.22 ± 0.35
···
10.00 ± 0.19
9.62 ± 0.19
7.23 ± 0.32
9.07 ± 0.28b
7.38 ± 0.32
···
9.52 ± 0.28
9.38 ± 0.28
MJ (CaOH)
7.43 ± 0.28
9.80 ± 0.16
7.25 ± 0.22
···
9.81 ± 0.23
9.38 ± 0.23
MJ
60.3 ± 7.7
22.9 ± 1.7
57.4 ± 5.7
20.0 ± 3.0e
21.5 ± 2.3
20.6 ± 2.2
dph
(pc)
M4.0
M5.5
M3.0
M7.0
M5.5
M5.0
Sp.
Type
N
N
N
?
?
?
20
pc?
Also identified by Phan-Bao et al. (2001).
See text for explanation of distance estimate.
Note. — Column 1 lists the designation from the NLTT catalog. Identifiers without prefixes are Luyten-Palomar (LP) Survey numbers.
Column 2 lists alternate designations. Columns 3 and 4 list the position of the 2MASS source. Column 5 lists the mr given in the NLTT.
Columns 6-8 list the infrared photometry from 2MASS. Columns 9-11 give the predicted MJ based on the spectral indices TiO 5, CaH
2, and CaOH. Column 12 gives our final estimate of MJ . Column 13 gives the distance estimates. Column 14 gives the spectral type.
Column 15 indicates whether the object lies within our distance limit of 20 pc (Y), within 1σ of the boundary (?), or beyond the limit (N).
f
e
LP 31-301 and LP 31-302 form a wide binary system with a separation of 500 . The bandstrength indices measured for the brighter star
fall in the ambiguous range, and we quote two distances estimates. The distance derived for the fainter star, LP 31-302, is consistent with
the shorter distance of 14.7 ± 1.2 pc.
This value is more than 3σ from either of the other predictions and was not used to estimate MJ .
d
c
This predicted value of MJ is double-valued and both predictions are more than 3σ from either of the other predictions. Neither are
incorporated in calculating the final value MJ .
b
a
This predicted value of MJ is double-valued and the result closest to the predictions based on other indices was used as our estimate
MJ .
701934878763763239-
NLTT/LP
Name
Table 2.2 (cont’d)
47
03
03
03
03
03
04
04
04
04
04
04
04
21
22
247- 47
413- 28
301- 44
357-206
889- 13
833- 40
890- 9
775- 35
358-478h
715- 41
776- 7
776- 26
698- 18
401- 24
34
40
54
55
55
06
16
38
38
39
44
52
37
58
07
12
53
00
03
11
12
30
34
43
52
56
06
12
33.38
54.92
51.03
36.89
47.79
52.38
31.15
47.47
54.45
04.93
46.17
27.95
17.33
04.47
22.50
27.48
42.45
44.37
11.81
36.36
19.73
24.88
29.51
13.83
33.94
27.00
01.73
27.53
00 06 47.47
00 07 22.50
00
00
00
01
01
01
02
02
02
02
02
02
03
03
G 267-33
704- 48
880-442d
α
(J2000)
880-441d
824-383i
150- 53
150- 58
706- 88
194- 35
469-162e
410- 38i
245- 52
651- 2
354-280f
771- 50
837- 37
831- 39g
Other
Name
NLTT/LP
Name
37
19
29
21
−27
−25
−28
−19
21
−09
−18
−19
−05
27
−29
−25
49
50
−11
41
12
16
36
−07
25
−16
−26
−21
40
29
57
18
09
17
18
42
47
59
40
54
27
30
35
28
42
55
26
27
49
48
13
29
04
27
47
31
01.87
47.44
34.46
48.15
08.15
30.72
52.60
20.60
48.57
01.24
58.80
46.11
44.39
36.48
25.67
00.72
51.39
44.76
50.37
53.20
26.46
26.29
11.10
01.35
37.27
36.62
43.35
22.00
−08 52 35.22
−29 35 17.00
δ
17.5
18.8
17.5
17.0
18.0
18.5
17.6
16.8
17.3
17.9
18.4
17.9
17.3
17.8
18.0
18.9
18.8
17.9
17.9
17.4
17.8
16.7
17.3
18.9
18.2
16.0
18.3
15.3
17.0
14.8
mr
Table 2.3.
12.246
13.194
12.492
12.057
12.735
12.726
12.256
11.941
12.485
12.610
12.987
12.580
12.237
12.762
13.017
13.155
13.014
12.476
12.621
12.209
12.794
11.843
12.459
13.066
12.491
11.748
12.660
11.648
11.970
11.285
J
11.773
12.605
11.899
11.422
12.139
12.148
11.662
11.403
11.899
11.968
12.390
11.980
11.655
12.096
12.481
12.543
12.467
11.881
12.048
11.594
12.192
11.258
11.822
12.483
11.943
11.129
12.078
11.079
11.409
10.745
H
11.400
12.232
11.610
11.086
11.840
11.813
11.330
11.090
11.509
11.699
12.066
11.586
11.268
11.811
12.135
12.092
12.039
11.504
11.667
11.244
11.811
10.949
11.457
12.134
11.566
10.764
11.660
10.648
11.059
10.518
Ks
10.27 ± 0.19
8.70 ± 0.19
7.72 ± 0.35
10.11 ± 0.19
9.81 ± 0.19
10.21 ± 0.19
10.00 ± 0.19
9.68 ± 0.19
9.97 ± 0.19
7.68 ± 0.35a
···
9.64 ± 0.19
10.71 ± 0.19
9.99 ± 0.19
9.52 ± 0.19
10.13 ± 0.19
8.78 ± 0.19
7.78 ± 0.35
10.46 ± 0.19
10.02 ± 0.19
10.00 ± 0.19
9.71 ± 0.19
10.25 ± 0.19
10.54 ± 0.19
9.70 ± 0.19
9.49 ± 0.19
9.85 ± 0.19
10.48 ± 0.19
10.25 ± 0.19
10.27 ± 0.19
10.02 ± 0.19
10.12 ± 0.19
MJ (TiO 5)
10.15 ± 0.19
8.50 ± 0.19
7.62 ± 0.33
9.64 ± 0.19
10.13 ± 0.19
9.98 ± 0.19
9.66 ± 0.19
9.56 ± 0.19
9.72 ± 0.19
7.30 ± 0.33
···
9.42 ± 0.19
10.62 ± 0.19
9.30 ± 0.19
9.38 ± 0.19
10.02 ± 0.19
8.73 ± 0.19
7.81 ± 0.33
10.25 ± 0.19
9.58 ± 0.19
9.00 ± 0.19b
9.51 ± 0.19
9.85 ± 0.19
10.26 ± 0.19
9.37 ± 0.19
9.25 ± 0.19
9.54 ± 0.19
9.85 ± 0.19
9.99 ± 0.19
9.99 ± 0.19
9.50 ± 0.19
9.72 ± 0.19
MJ (CaH 2)
10.27 ± 0.28
8.80 ± 0.28
7.85 ± 0.32
10.86 ± 0.28
5.65 ± 0.32c
9.45 ± 0.28
9.64 ± 0.28
9.25 ± 0.28
8.98 ± 0.28b
7.31 ± 0.32
···
9.32 ± 0.28
9.84 ± 0.28
9.09 ± 0.28a
9.06 ± 0.28a
8.98 ± 0.28b
8.97 ± 0.28
8.02 ± 0.32
10.45 ± 0.28
7.70 ± 0.32c
9.89 ± 0.28
9.14 ± 0.28a
10.95 ± 0.28
10.01 ± 0.28
9.01 ± 0.28a
9.63 ± 0.28
9.16 ± 0.28a
10.70 ± 0.28
6.07 ± 0.32c
9.43 ± 0.28
9.36 ± 0.28
9.09 ± 0.28b
MJ (CaOH)
Data for Targets Not Included in NLTT Sample 1
10.22 ± 0.13
8.64 ± 0.17
7.73 ± 0.21
10.06 ± 0.52
9.97 ± 0.21
9.97 ± 0.34
9.80 ± 0.21
9.55 ± 0.22
9.84 ± 0.18
7.42 ± 0.26
···
9.49 ± 0.18
10.51 ± 0.41
9.54 ± 0.40
9.38 ± 0.23
10.07 ± 0.14
8.79 ± 0.16
7.88 ± 0.22
10.37 ± 0.16
9.80 ± 0.26
9.97 ± 0.17
9.52 ± 0.26
10.22 ± 0.47
10.33 ± 0.25
9.44 ± 0.31
9.42 ± 0.20
9.59 ± 0.30
10.26 ± 0.38
10.12 ± 0.19
10.00 ± 0.37
9.68 ± 0.31
9.92 ± 0.24
MJ
22.4 ± 1.4
33.9 ± 2.7
51.6 ± 5.0
40.1 ± 9.4
43.6 ± 4.2
41.0 ± 6.4
34.5 ± 3.3
41.3 ± 4.2
29.8 ± 2.5
119.7 ± 14.3
18.0 ± 5.0
39.4 ± 3.2
33.0 ± 6.1
39.6 ± 7.3
29.9 ± 3.1
33.0 ± 2.2
37.3 ± 2.7
57.0 ± 5.8
23.8 ± 1.7
48.1 ± 5.7
32.0 ± 2.5
32.4 ± 3.9
32.6 ± 7.0
30.4 ± 3.5
37.0 ± 5.2
32.1 ± 2.9
38.2 ± 5.3
29.9 ± 5.2
37.6 ± 3.2
33.3 ± 5.6
32.7 ± 4.6
37.2 ± 4.2
dph
(pc)
M6.0
M5.5
M5.5
M5.0
M6.0
M6.0
M5.0
M5.0
M5.5
M6.0
M6.0
M6.0
M5.5
M5.5
M5.5
M5.5
M6.0
M5.5
M5.5
M5.5
M4.0
sdM6.0
M5.0
M6.5
M5.5
M5.0
M6.0
M4.0
M6.0
M3.5
Sp.
Type
48
LHS 3970
Other
Name
23
23
23
23
23
10
17
33
38
59
02.79
20.72
40.57
55.41
03.90
α
(J2000)
−06
−02
−21
43
−29
05
36
33
00
32
δ
53.37
32.41
52.44
15.27
22.68
18.4
17.2
16.5
16.8
18.3
mr
13.004
12.304
11.913
11.945
12.382
J
12.405
11.662
11.327
11.367
11.847
H
12.017
11.275
10.955
11.042
11.505
Ks
···
9.89 ± 0.19
10.08 ± 0.19
9.59 ± 0.19
10.32 ± 0.19
MJ (TiO 5)
···
9.62 ± 0.19
9.79 ± 0.19
9.18 ± 0.19
9.93 ± 0.19
MJ (CaH 2)
···
9.27 ± 0.28
10.20 ± 0.28
9.03 ± 0.28a
7.58 ± 0.32c
MJ (CaOH)
10.15 ± 0.16
9.67 ± 0.28
9.98 ± 0.21
9.32 ± 0.26
10.13 ± 0.24
MJ
37.0 ± 5.0
34.0 ± 4.4
24.4 ± 2.4
33.8 ± 4.1
28.4 ± 3.1
dph
(pc)
M6.0:
M5.5
M5.5
M5.0
M6.0
Sp.
Type
Note. — The columns are the same as the previous table.
Candidate M subdwarf, see §§2.5.1 and 2.6.2
Has common proper motion with G 8-48.
h
i
Has common proper motion with LP 831-38.
Has common proper motion with G 36-39.
Has common proper motion with G 4-5.
g
f
e
LP 880-441 and LP 880-442 form a wide binary system with separation of 800 . As with LP 31-301/302, the brighter star has indices
which fall within the region of ambiguity in Figure 2.4. However, in this case the distance estimate to the fainter star is not sufficiently
accurate to provide an improved distance estimate to the system.
This value is more than 3σ from either of the other predictions and was not used to estimate MJ .
d
c
This predicted value of MJ is double-valued and both predictions are more than 3σ from either of the other predictions. Neither
are incorporated in calculating the final value MJ .
b
This predicted value of MJ is double-valued and the result closest to the predictions based on other indices was used as our estimate
MJ .
a
702- 1i
702- 58
878- 3
239- 33
880-140
NLTT/LP
Name
Table 2.3 (cont’d)
Table 2.4.
Regions That Define the Spectroscopic Indices
Index
Numerator (Å)
Denominator (Å)
Ref
CaOH
Hα
CaH 1
CaH 2
CaH 3
TiO-a
TiO 2
TiO 3
TiO 4
TiO 5
VO-a
PC3
6230–6240
6560–6566
6380–6390
6814–6846
6960–6990
7033–7048
7058–7061
7092–7097
7130–7135
7126–7135
Sum of 7350–7370 and 7550–7570
8230–8270
6345–6354
6545–6555
Avg. of 6345–6355 and 6410–6430
7042–7046
7042–7046
7058–7073
7043–7046
7079–7084
7115–7120
7042–7046
7430–7470
7540–7580
1
1
1
1
1
2
1
1
1
1
2
3
References. — (1) Kirkpatrick et al. (1999); (2) PMSU1; (3) Martı́n et al. (1999)
49
50
2MASS
Name
2MASSI0006−0852
2MASSI0007225−293526
2MASSI0007225−293517
2MASSI0012−2528
2MASSI0020+3305
2MASSI0021+1843
2MASSI0035−0541
2MASSI0053+4942
2MASSI0100+5055
2MASSI0103−1126
2MASSI0109−0343
2MASSI0111+4127
2MASSI0112+1502
2MASSI0133−1738
2MASSI0203+2134
2MASSI0212+1249
2MASSI0214−0357
2MASSI0218−0617
2MASSI0230+1648
2MASSI0234+3613
2MASSI0241−0432
2MASSI0243−0729
2MASSI0250−0808
2MASSI0252+2504
2MASSI0256−1627
2MASSI0305+2742
2MASSI0306−2647
2MASSI0312−2131
2MASSI0331−3042
2MASSI0334+3740
2MASSI0338+3828
2MASSI0340+1929
2MASSI0350+1818
2MASSI0354+2957
2MASSI0355+2118
2MASSI0355−2709
2MASSI0405574+711641
Name
LP 704- 48
LP 880-442
LP 880-441
LP 824-383
LP 292- 67
LP 405- 5
LP 645- 53
LP 150- 53
LP 150- 58
LP 706- 88
LP 647- 13
LP 194- 35
LP 467- 17
LP 768-113
LP 352- 79
LP 469-162
LP 649- 72
LP 649- 93
LP 410- 38
LP 245- 52
G 75-35
LP 651- 2
LP 651- 17
LP 354-280
LP 771- 50
LP 299- 15
LP 837- 37
LP 831- 39
LP 888- 18
LP 247- 47
LP 247- 56
LP 413- 28
LP 413- 53
LP 301- 44
LP 357-206
LP 889- 13
LP 31-301
0.209
0.411
0.129
0.884
0.316
0.290
0.330
0.321
0.295
0.349
0.559
0.386
0.332
0.417
0.382
0.489
0.312
0.437
0.286
0.339
0.372
0.268
0.293
0.371
0.375
0.362
0.386
0.387
0.570
0.184
0.324
0.432
0.692
0.261
0.364
0.117
0.423
0.952
0.933
0.906
1.512
0.942
1.106
0.989
1.336
1.585
1.877
2.050
1.802
0.906
1.198
3.641
0.949
1.862
1.512
1.962
1.769
1.329
1.192
1.380
0.995
1.565
1.862
4.255
1.050
2.029
0.920
1.023
1.464
2.254
1.149
1.699
1.207
1.001
Hα
0.793
0.807
0.826
1.146
0.787
0.783
0.858
0.783
0.795
0.747
0.969
0.880
0.883
0.790
0.744
0.862
0.799
1.035
0.627
0.785
0.763
0.863
0.868
0.883
0.768
0.774
0.754
0.782
1.017
0.733
0.770
0.803
0.942
0.756
0.813
1.262
0.808
CaH 1
0.252
0.429
0.307
0.255
0.333
0.325
0.368
0.271
0.305
0.316
0.497
0.299
0.347
0.438
0.314
0.473
0.315
0.300
0.243
0.331
0.395
0.202
0.318
0.344
0.335
0.331
0.266
0.405
0.284
0.242
0.328
0.314
0.319
0.376
0.321
0.285
0.424
CaH 2
0.566
0.686
0.588
0.444
0.654
0.620
0.685
0.547
0.603
0.622
0.791
0.628
0.687
0.686
0.584
0.746
0.621
0.603
0.480
0.602
0.647
0.532
0.640
0.681
0.599
0.608
0.541
0.654
0.567
0.580
0.635
0.624
0.754
0.551
0.617
0.655
0.687
CaH 3
2.397
1.484
2.113
2.970
2.123
1.915
1.873
2.643
2.261
2.262
1.691
2.393
2.040
1.459
2.235
1.500
2.297
2.842
2.250
2.158
1.674
2.764
2.199
2.265
2.094
2.172
3.264
1.488
3.113
2.566
1.937
2.354
2.605
2.208
2.205
2.342
1.523
TiO-a
0.334
0.616
0.419
0.238
0.416
0.452
0.468
0.328
0.372
0.393
0.555
0.348
0.427
0.621
0.411
0.615
0.370
0.319
0.396
0.417
0.551
0.301
0.405
0.442
0.442
0.427
0.263
0.597
0.286
0.324
0.444
0.359
0.358
0.381
0.405
0.405
0.588
TiO 2
0.614
0.705
0.605
0.545
0.555
0.591
0.621
0.511
0.562
0.612
0.794
0.590
0.599
0.714
0.587
0.712
0.569
0.386
0.523
0.623
0.652
0.497
0.583
0.563
0.630
0.609
0.543
0.779
0.598
0.613
0.620
0.416
0.576
0.536
0.636
0.464
0.696
TiO 3
Spectral Indices of NLTT Targets and Standards
CaOH
Table 2.5.
0.462
0.663
0.476
1.192
0.542
0.506
0.542
0.592
0.530
0.596
0.826
0.571
0.531
0.641
0.565
0.656
0.545
0.497
0.580
0.585
0.596
0.391
0.550
0.510
0.593
0.581
0.665
0.619
0.559
0.454
0.520
0.553
0.694
0.527
0.571
0.397
0.621
TiO 4
0.209
0.421
0.230
0.272
0.251
0.264
0.292
0.217
0.245
0.288
0.504
0.249
0.261
0.438
0.284
0.428
0.250
0.220
0.246
0.294
0.381
0.150
0.251
0.247
0.310
0.306
0.228
0.410
0.217
0.183
0.273
0.243
0.292
0.245
0.284
0.212
0.396
TiO 5
2.052
1.917
2.012
2.075
2.070
2.012
2.025
2.106
2.032
2.130
2.369
2.108
2.054
1.960
2.055
1.952
2.065
2.202
2.019
2.066
1.981
2.137
2.111
2.032
2.025
2.027
2.132
1.944
2.208
2.096
2.025
2.071
2.180
2.047
2.047
2.152
1.974
VO-a
1.331
0.912
1.210
1.257
1.207
1.214
1.106
1.383
1.172
1.283
1.947
1.267
1.177
0.882
1.156
0.966
1.181
1.411
1.290
1.289
0.932
1.176
1.218
1.022
1.141
1.255
1.354
0.891
1.707
1.340
1.184
1.413
1.554
1.247
1.236
1.129
1.019
PC3
51
2MASS
Name
2MASSI0405565+711639
2MASSI0406−2517
2MASSI0410−1251
2MASSI0413−2704
2MASSI0416−2818
2MASSI0435−1606
2MASSI0438−1942
2MASSI0438+2147
2MASSI0439−0959
2MASSI0439+1615
2MASSI0440−0530
2MASSI0444−1840
2MASSI0452−1058
2MASSI0452−1954
2MASSI2102+2237
2MASSI2116+2238
2MASSI2129−1855
2MASSI2132−0511
2MASSI2137−0527
2MASSI2151−0127
2MASSI2236+3655
2MASSI2248+1232
2MASSI2254+2527
2MASSI2258+2730
2MASSI2301−0539
2MASSI2310−0605
2MASSI2317−0236
2MASSI2322−2725
2MASSI2323−2232
2MASSI2333−2133
2MASSI2337−0838
2MASSI2337−1250
2MASSI2338+4300
2MASSI2347+4238
2MASSI2359−2932
Name
LP 31-302
LP 833- 40
LP 714- 37
LP 890- 2
LP 890- 9
LP 775- 31
LP 775- 35
LP 358-478
LP 715- 41
LP 415-302
LP 655- 48
LP 776- 7
LP 716- 10
LP 776- 26
LP 396- 18
LP 397- 10
LP 817- 54
LP 698- 2
LP 698- 18
LP 638- 50
LP 288- 40
LP 521- 18
LP 401- 10
LP 401- 24
LP 701- 59
LP 702- 1
LP 702- 58
LP 934- 33
LP 878- 90
LP 878- 3
LP 763- 38
LP 763- 3
LP 239- 33
LP 239- 52
LP 880-140
DG ERI
GJ 1224
0.291
0.245
0.320
0.297
0.383
0.277
0.297
0.361
0.151
0.292
0.357
0.736
0.256
0.324
0.416
0.305
0.312
0.338
0.334
0.299
0.325
0.326
0.352
0.371
0.501
0.287
0.347
0.374
0.478
0.219
0.432
0.312
0.379
0.332
0.449
0.480
0.347
CaOH
1.854
1.085
1.306
2.672
0.990
1.444
0.963
1.647
1.925
1.171
2.460
1.032
0.943
1.327
0.939
1.434
0.983
1.059
0.940
1.332
0.968
1.709
2.022
0.771
0.975
0.867
1.704
1.668
0.995
0.958
2.084
1.870
0.926
0.926
0.914
0.955
1.586
Hα
0.803
0.717
0.815
0.841
0.857
0.870
0.853
0.802
0.811
0.803
0.877
0.840
0.841
0.762
0.828
0.805
0.872
0.868
0.875
0.787
0.771
0.777
0.804
0.794
0.804
0.696
0.811
0.793
0.810
0.779
1.089
0.779
0.744
0.837
0.896
0.998
0.755
CaH 1
0.314
0.241
0.328
0.277
0.336
0.249
0.349
0.318
0.285
0.321
0.284
0.270
0.333
0.269
0.426
0.288
0.334
0.331
0.322
0.307
0.365
0.318
0.289
0.299
0.461
0.287
0.309
0.299
0.495
0.291
0.271
0.296
0.357
0.360
0.276
0.547
0.359
CaH 2
0.597
0.452
0.635
0.593
0.649
0.545
0.664
0.598
0.497
0.611
0.597
0.601
0.648
0.579
0.708
0.607
0.653
0.688
0.620
0.588
0.631
0.593
0.573
0.624
0.756
0.611
0.610
0.561
0.733
0.602
0.574
0.576
0.631
0.671
0.594
0.864
0.621
CaH 3
Table 2.5 (cont’d)
2.159
2.291
2.119
2.572
2.062
3.027
1.901
2.068
2.712
1.993
2.918
2.114
1.974
2.593
1.613
2.456
1.970
2.047
2.092
2.133
1.701
2.347
2.430
2.197
1.516
2.445
2.444
2.306
1.341
2.196
2.916
2.502
1.733
1.857
2.811
1.796
1.807
TiO-a
0.414
0.380
0.403
0.297
0.468
0.316
0.510
0.428
0.349
0.429
0.303
0.365
0.436
0.347
0.548
0.354
0.457
0.458
0.417
0.400
0.511
0.387
0.352
0.393
0.622
0.414
0.363
0.385
0.674
0.407
0.265
0.355
0.491
0.492
0.307
0.543
0.498
TiO 2
0.601
0.345
0.597
0.563
0.565
0.558
0.604
0.670
0.571
0.589
0.613
0.448
0.571
0.464
0.678
0.526
0.561
0.555
0.541
0.583
0.623
0.613
0.556
0.554
0.697
0.550
0.599
0.600
0.752
0.528
0.460
0.557
0.595
0.609
0.460
0.649
0.621
TiO 3
0.577
0.459
0.512
0.533
0.572
0.541
0.489
0.571
0.422
0.522
0.597
0.577
0.500
0.534
0.610
0.524
0.575
0.552
0.506
0.514
0.588
0.561
0.561
0.440
0.628
1.155
0.579
0.520
0.702
0.499
0.373
0.543
0.541
0.558
0.413
0.683
0.586
TiO 4
0.291
0.172
0.259
0.228
0.286
0.210
0.314
0.266
0.181
0.264
0.245
0.212
0.252
0.209
0.369
0.232
0.294
0.264
0.243
0.270
0.320
0.271
0.259
0.229
0.422
0.399
0.260
0.259
0.517
0.234
0.175
0.245
0.301
0.296
0.202
0.396
0.338
TiO 5
2.026
2.072
2.059
2.106
2.008
2.201
2.019
2.032
2.029
2.013
2.205
2.144
2.051
2.049
1.984
2.090
2.047
2.098
2.062
2.033
1.968
2.047
2.074
2.056
1.954
2.123
2.042
2.015
1.946
2.056
2.277
2.052
1.991
2.026
2.071
1.910
1.988
VO-a
1.225
1.388
1.230
1.372
1.224
1.598
0.962
1.247
1.197
1.040
1.658
1.221
1.195
1.229
1.068
1.334
1.164
1.109
1.184
1.091
1.116
1.220
1.263
1.237
0.969
1.255
1.173
1.239
0.944
1.148
1.489
1.190
1.133
1.168
1.301
0.959
1.162
PC3
52
GJ 1227
GJ 1245
GL 643
GL 699
GL 720B
GL 752A
GL 83.1
LHS 3406
LHS 1326
LHS 17
VB 10
VB 8
Name
2MASS
Name
0.373
0.298
0.399
0.387
0.416
0.531
0.332
0.288
0.239
0.257
0.515
0.277
CaOH
0.950
1.287
0.980
0.949
0.957
0.969
1.136
2.656
1.017
0.935
1.310
1.386
Hα
0.803
0.753
0.780
0.761
0.827
0.836
0.773
0.599
0.779
0.794
0.948
0.759
CaH 1
0.391
0.308
0.430
0.400
0.440
0.545
0.362
0.307
0.299
0.285
0.343
0.225
CaH 2
0.668
0.575
0.685
0.654
0.697
0.780
0.619
0.676
0.618
0.581
0.643
0.497
CaH 3
1.672
2.136
1.456
1.472
1.485
1.308
1.691
2.484
2.200
1.966
2.410
3.214
TiO-a
Table 2.5 (cont’d)
0.534
0.415
0.643
0.608
0.611
0.730
0.537
0.400
0.423
0.430
0.383
0.291
TiO 2
0.648
0.573
0.694
0.715
0.724
0.764
0.649
0.305
0.572
0.511
0.656
0.495
TiO 3
0.589
0.556
0.639
0.608
0.621
0.730
0.592
0.590
0.517
0.467
0.661
0.489
TiO 4
0.343
0.274
0.432
0.400
0.401
0.554
0.345
0.266
0.262
0.243
0.304
0.167
TiO 5
1.973
2.050
1.966
1.963
1.947
1.949
2.003
2.253
2.044
1.979
2.297
2.143
VO-a
1.091
1.287
1.071
0.990
0.881
0.894
1.003
1.260
1.229
1.151
1.767
1.627
PC3
Table 2.6.
Name
LP
LP
LP
LP
LP
405150150706647-
2MASS
Name
5
53
58
88
13
2MASSI0021+1843
2MASSI0053+4942
2MASSI0100+5055
2MASSI0103−1126
2MASSI0109−0343
LP
Activity of NLTT Sample
10
−15
Hα flux
ergs cm−2 sec−1
5.51
0.85
4.58
2.67
2.75
Hα
EW (Å)
mbol
log
Fα
Fbol
2.3
13.27
−4.36
4.2
14.95
−4.50
6.4
14.41
−3.99
8.2
14.53
−4.17
10.SI00411(16053)]TJ/F238.96Tf232.620TD[( )]T
−0
−23409.4589500(0.2)-25110.7053
13 2MAS
−
Chapter 3
Meeting the Cool Neighbors. V. A
2MASS-Selected Sample of
Ultracool Dwarfs
The goal of this dissertation is a robust measurement of the luminosity function of low-mass
stars and brown dwarfs. This is accomplished by compiling a sample of ultracool objects within
20 pc of the Sun from the 2MASS Second Incremental Release. This chapter details the creation of
the 2MU2 sample and presents the first results from the spectroscopic follow-up of that sample and
represents the central part of this dissertation. It should be noted that the analysis presented in
§ 3.7 is only for 66% of the ultracool candidates and the complete dataset is discussed in Chapter 4.
What follows is a reprinting of a paper published in the Astronomical Journal in November
2003 and was written in collaboration with Neill Reid, James Liebert, Davy Kirkpatrick, and Patrick
Lowrance. I am the primary author of the text, although authors Lowrance and Kirkpatrick had
significant influence on the discussion of carbon dwarfs and low-gravity (young) objects—all authors
aided in data acquisition. I am responsible for the creation of the sample, although the specific
selection criteria were decided upon through extensive consultation with Reid and Liebert. I built
and maintain the extensive database to keep track of the candidates. I am responsible for creating
the target lists for all observing runs and the data reduction and analysis. As a result, the data
reduction and spectral type estimates are all self-consistent. In addition, I compiled the sample
characteristics and the luminosity function estimate. Finally, Reid led the effort to analyze the
bright (J < 9) objects in the sample.
54
3.1
Abstract
We present initial results of our effort to create a statistically robust, volume-limited sample of
ultracool dwarfs from the 2MASS Second Incremental Data Release. We are engaged in a multifaceted search for nearby late-type dwarfs and this is the first installment of our search using purely
photometric selection. The goal of this work is a determination of the low-mass star and brown
dwarf luminosity function in the infrared. Here, we outline the construction of the sample, dubbed
2MU2, and present our first results, including the discovery of 186 M7–L6 dwarfs—47 of these are
likely to be within 20 pc of the Sun. These results represent 66% of the ultracool candidates in our
sample yet constitute an 127% increase in the number of ultracool dwarfs known within the volume
searched (covering 40% of the sky out to 20 pc). In addition, we have identified 10 M4–M6.5 objects
that are likely to be within 20 pc (or within 1σ). Finally, based on these initial data, we present
a preliminary luminosity function and discuss several interesting features of the partial sample presented here. Once our sample is complete, we will use our measured luminosity function to constrain
the mass function of low-mass stars and brown dwarfs.
3.2
Introduction
Ultracool dwarfs (spectral types M7 and later) include stars and brown dwarfs and can have
masses as small as several Jupiter masses. The search for these ultracool dwarfs has been greatly
enabled by three recent deep, wide-sky surveys: the Two-Micron All Sky Survey (Skrutskie 2001,
2MASS), the Deep Near Infrared Southern Sky survey (Epchtein et al. 1999, DENIS), and the Sloan
Digital Sky Survey (York et al. 2000, SDSS).
Two methods are used to identify late-type dwarfs in these large data sets: direct query of the
survey’s photometric data products; and using those data in combination with new and existing
proper motion data and optical photometry. The former method has yielded close to 200 L dwarfs
and over 180 ultracool M dwarfs in the three surveys (notable for quantity are Phan-Bao et al.
(2003, 2001); Schneider et al. (2002); Hawley et al. (2002); Gizis et al. (2000); Kirkpatrick et al.
(2000, 1999); Martı́n et al. (1999)). The other tack has unveiled many previously unknown late-type
members of our Solar neighborhood (if not as many L dwarfs). Near-infrared photometry from
DENIS and 2MASS has been combined with Luyten’s proper motion catalogs (Luyten (1979, LHS),
Luyten (1979, NLTT)), new proper-motion catalogs (Lépine, Shara, & Rich 2002), and with new
and existing optical photometry to identify nearly 200 M dwarfs but less than 10 L dwarfs within
35 pc of the Sun (Salim, Lépine, Rich, & Shara 2003; Lépine, Rich, & Shara 2003; Reylé, Robin,
Scholz, & Irwin 2002; Lodieu, Scholz, & McCaughrean 2002; Scholz & Meusinger 2002; Reid & Cruz
2002; Reid, Kilkenny, & Cruz 2002; Cruz & Reid 2002; EROS Collaboration et al. 1999).
While both methods have yielded many discoveries, both have biases and limitations that make
it difficult to use these data sets to study the new population of ultracool dwarfs statistically. The use
55
of proper motion and optical data has the advantage of finding the nearest objects but this type of
study is restricted to bright magnitudes and hence, earlier-type objects. In addition, proper motion
searches are strongly biased towards objects with intrinsically high space motions with respect to
the Sun. Photometric searches avoid a kinematic bias and probe much larger spatial volumes by
reaching fainter magnitudes than proper motion surveys. However, previous photometric searches
are characterized by small sky coverage and/or restrictive color-criteria.
Our aim is to use both proper motion and photometric searches to complete the census of the
nearest ultracool dwarfs. In the first three papers in this series (Reid & Cruz 2002; Reid, Kilkenny,
& Cruz 2002; Cruz & Reid 2002, hereafter Papers I, II, & III) we presented the first results of our
effort to cross-reference the 2MASS Second Incremental Release with the NLTT catalog. While we
uncovered nearly 150 new objects within 20 pc, most of them are early and mid-M dwarfs. Reid et al.
(2003) (hereafter Paper IV) presented the discovery of an M8.5 dwarf within 6 pc found in the course
of the program described in this Paper. Here, we present the initial results and the methodology
of our photometric search of the 2MASS Second Incremental Release for nearby objects cooler than
spectral type M6.
Building on this foundation, we have created a statistically robust sample of ultracool dwarfs
from the 2MASS Second Incremental Release that is complete within 20 pc of the Sun for spectral
types M7 to L8. The sample is dubbed 2MU2—2MASS ultracool dwarfs from the Second Data
Release. This volume-limited sample permits detailed investigation of the overall range of properties
of these low-mass objects which span the stellar/brown dwarf boundary. In particular, once the
observations are complete, we will have an infrared luminosity function which we will use to constrain
the mass function of low-mass stars and brown dwarfs.
The current knowledge of the field mass function of low-mass stars is based primarily on two
projects: the Palomar/Michigan State University Nearby-Star Spectroscopic Survey (Reid, Hawley,
& Gizis 1995; Reid, Gizis, & Hawley 2002); and the 8 pc sample (Reid & Gizis 1997; Reid et al. 1999,
2003) (hereafter PMSU and 8 pc sample). Both datasets yield a mass function that is consistent
with a power-law distribution (Ψ(M ) = M −α ) with α = 1.2 at low masses (M < 0.6M¯ ) (see Figure
12 of Reid, Gizis, & Hawley (2002)). However, both samples only extend to 0.08M¯ —just above
the stellar/brown dwarf boundary for solar metallicity objects. Reid et al. (1999) made the first
attempt to extend coverage to substellar mass objects in the field, but their study is hampered by
sparse statistics. The project described in this Paper is the first concerted effort focused on studying
the field mass function in the regime of low-mass stars and brown dwarfs.
This is the fifth paper in a series that report results of our multifaceted study of nearby late-type
objects in the immediate Solar neighborhood. While the previous papers in the series have concentrated on objects with large proper motions, here we present our first results of purely photometric
selection of candidate nearby dwarfs using the 2MASS survey. In § 3.3 we describe the creation of
the 2MU2 sample. We present our observations in § 3.4 and the spectral type and absolute magni-
56
tude calibrations in § 3.5. We discuss interesting objects in § 3.6 and present the characteristics of
the portion of the 2MU2 sample presented here and a preliminary luminosity function in § 3.7. Our
conclusions are in § 3.8.
3.3
The 2MU2 Sample
The primary goal of this project is to create a sample of ultracool dwarfs within 20 pc using
the 2MASS Second Incremental Data Release. This catalog covers 48% of the sky and contains over
162 million point sources with J (1.25 µm), H (1.65 µm), and KS (2.17 µm) photometry and highly
accurate astrometry. While we use several methods to refine the 2MU2 sample, as described in
detail below, there are three primary selection criteria. The first requires targets to have a galactic
latitude greater than 10◦ in order to avoid the Galactic plane. Two additional cuts are based on the
JHKS color-color and color-magnitude sequences of M and L dwarfs with trigonometric parallax
measurements. The final 2MU2 sample of viable candidates contains 1225 targets and covers 40%
(16,350 sq. deg.) of the sky. Full details of the selection procedures are given in this section.
3.3.0.1
Selection Criteria
The initial 2MASS query, using the Gator tool provided by IRSA1 , required |b| > 10◦ , J −KS >
1, and rejected extended objects. These criteria selected ∼11.3 million sources. Custom built IDL
code was used to further cut the sample in a series of steps which are detailed below and summarized
in Table 3.1.
Cataloged Cloud and Dense Regions: Objects which are associated with star-formation regions (e.g. Orion, Lupus, etc.) were eliminated from the outset. Rough positions and dimensions for those reddening regions were obtained from Dame et al. (1987) and Dutra & Bica
(2002). However, since the high density of sources persisted on the fringes of those regions,
we enlarged the areas excluded from our sample. The positions of those regions are listed in
Table 3.2. In addition, the dense stellar associations of the LMC, SMC, 47 Tuc, M31, and M33
were also excluded. A total of ∼1.65 million sources were eliminated based on these, reducing
the sample to ∼9.65 million targets. These cuts are taken into account in computing the total
areal coverage of the final 2MU2 sample.
J/(J−KS ): Our goal is to identify nearby objects of spectral types M7 and later. This is accomplished with two cuts in J/(J − KS ). The left panel of Figure 3.1 is the color-magnitude
diagram for the tail end of the main sequence as it would appear if all of the objects were at
20 pc (MJ + 1.51). A color-magnitude diagram for a typical 1◦ region of the 2MASS database
1 http://irsa.ipac.caltech.edu/
57
is shown in the right panel. We selected objects that meet both of the following criteria:
(J − KS ) > 1.0
J ≤ 3(J − KS ) + 10.5.
(3.1)
The (J − KS ) > 1 criterion eliminates most objects earlier than M7. Objects that are farther
away than 20 pc should fall below the line formed by the second criterion while nearby objects
lie above it. These criteria have the biggest effect on narrowing our sample by cutting ∼9.41
million sources, leaving ∼236,500.
One calibrating object (2M 1632, L8) lies just below our line in the JKS plane and just above
the scatter of the main sequence easily visible in the right panel of Figure 3.1. In our effort to
balance sample completeness with manageable size, we made the JKS cut such that numerous
faint main-sequence stars would be excluded rather than accommodate this blue-ish L8 dwarf.
These criteria were not intended to select for T dwarfs however some early-type examples may
fall within our sample (see 2M 0423 in § 3.6.1).
(H−KS )/(J−H): To further refine the spectral type distribution of the sample, color cuts were
applied in the JHKS plane. Figure 3.2 shows the color-color diagram for the same objects as
in Figure 3.1 and our selection criteria:
(J − H) ≤ 0.8
(J − H) ≤ 1.75(H − KS ) + 0.1875
)
(J − H) ≥ 1.75(H − KS ) − 0.4750
for 0.30 ≤ (H − K) ≤ 0.35
for 0.35 < (H − K) ≤ 1.20.
(3.2)
In addition, the (J − KS ) > 1 criterion translates to
(J − H) > 1 − (H − K)
in JHKS color-color space. These criteria isolate late-M and L dwarfs and exclude the central
region of the giant sequence. This reduced the sample by ∼228,000 objects, leaving 8531
targets.
Figure 3.2 plots these objects from Kirkpatrick et al. (1999, 2000) whose uncertainties are less
than 0.1 magnitudes. About 15% of all of the L dwarfs listed in Kirkpatrick et al. (1999,
2000) scatter outside of our JHKS cuts. The objects that fall outside of our criteria are
among the faintest known L dwarfs with large uncertainties in their colors (between 0.1 and
0.3 magnitudes). Extending the sample to include those regions is not feasible since it would
introduce an unmanageable number of unwanted interlopers.
J/(R−J): Included in the 2MASS data products is BR optical photometry for point sources with
a counterpart in the Tycho or USNO catalogs within 500 of the 2MASS position. For objects
where an R magnitude is available, we have applied a cut in J/(R − J) to restrict the sample
58
to objects with optical/NIR colors that are consistent with nearby late-type dwarfs. Figure 3.3
shows the color-magnitude diagram for cool stars with known parallaxes where the apparent
magnitudes have been shifted to as they would appear if at a distance of 20 pc (MJ + 1.51).
Targets with an available R magnitude (∼ 40%) are required to meet the following criteria:


3.50(R − J) + 3.00, for (R − J) ≤ 1.0,




 1.67(R − J) + 4.83, for 1.0 < (R − J) ≤ 2.8,
(3.3)
J≤

5.50(R
−
J)
−
5.90,
for
2.8
<
(R
−
J)
≤
3.0,




 1.16(R − J) + 7.12, for 3.0 < (R − J) ≤ 5.5.
This cut 5337 objects, leaving 3194 targets.
Giants: Bessell & Brett (1988) have shown that some types of giants have colors that meet our
JHKS color criteria and as a result, many M giants persisted in the sample. Figure 3.2 shows
data for giants in JHKS color space. Noting that giants tend to have bluer (H − KS ) colors
and very bright magnitudes (J < 10), we are able to get rid of a significant portion of the
giants by eliminating objects that meet both of the following criteria. (Note that the previous
items have been criteria for inclusion while the following criteria are for exclusion.)
J < 10
(J − H) > 2(H − KS ), for 0.375 < (H − KS ) < 0.470.
(3.4)
This cut 698 objects, leaving 2496 targets. The second criterion is shown in Figure 3.2.
Flags: The 2MASS catalog also provided flags for possible photometric confusion and solar system
objects (cc flg=000 and mp flg=0). The confusion flag indicates when more than one object is
merged and the individual photometry could not be resolved. The solar system flag indicates
the point source is associated with a minor planet. Three hundred ten objects were cut based
on these flags, leaving 2186.
Uncataloged Reddening Regions: Even though we cut objects at low galactic latitudes and
near star-forming regions, there were still several large areas of high density near the plane.
These regions are listed in Table 3.3 and are likely to be reddened sources associated with
small/uncataloged molecular clouds, so we have eliminated them. This removed 514, leaving
a sample size of 1672 targets.
3.3.1
Refining the Faint Portion of the 2MU2 Sample
The color-color and color-magnitude diagrams of the 1672 surviving candidates are shown in
Figure 3.4. At this point, the 588 objects with J ≤ 9 were set aside for separate classification and
are discussed in § 3.3.2. The 1084 objects with J > 9 were examined in more detail and 447 objects
were eliminated based on the following considerations which are summarized in Table 3.4:
59
(F−J)/(J−KS ): Additional optical photometry was obtained from the Guide Star Catalog 2.2
(Morrison et al. 2001, GSC). (F − J) and (J − KS ) colors were used to eliminate objects that
are too blue at optical wavelengths to be ultracool dwarfs. Targets were required to meet the
following criteria:
(
(F − J) >
4.0
1.67(J − K) + 2.33.
(3.5)
This eliminated 137 objects. Recently, Thorstensen & Kirkpatrick (2003), identify one of these
eliminated objects as a nearby L dwarf. As suggested by those authors, crowding in the field
likely resulted in a mismatch between the 2MASS source and the GSC source and thus an
aberrant (F − J) color. All of these 137 objects will be examined by eye to correct for other
possible mismatches and will be discussed in a future paper.
Visual Inspection: Two hundred and eleven targets were eliminated via visual inspection of POSS
plates and 2MASS images. The images revealed some sources to be artifacts of the 2MASS
data, associated with large galaxies or globular clusters, or clearly non-red objects.
SIMBAD: Twenty four objects were eliminated because they are listed in SIMBAD as known
carbon stars, pre-main sequence objects, or quasars.
Clouds: Both SIMBAD and visual inspection enabled us to identify 41 objects associated with
molecular clouds or reddening regions. These were eliminated.
Bland: Figure 3.4 shows the color-magnitude and color-color diagrams for the 588 bright objects
as well as the surviving faint targets. As can be seen in the left panel there is a high density of
faint objects with colors close to (J − KS ) = 1. The high density of mid-M dwarfs just bluer
than (J − KS ) = 1 and the increased photometric uncertainties at fainter magnitudes leads
to more scatter into our sample. After many observations of objects in this color space, we
were able to confidently eliminate 34 objects with J − KS < 1.1 and J > 13 as distant mid-M
dwarfs.
These cuts reduced the 2MU2 sample of J > 9 objects to 637 ultracool candidates. Table 3.5
lists the 112 ultracool targets with existing data (predominately from Kirkpatrick et al. (1999, 2000);
Gizis et al. (2000)). The remaining 525 require spectroscopic follow-up observations—data for 307
are presented here.
3.3.2
The Brightest Candidates
Five hundred and eighty-eight of the ultracool dwarf candidates have apparent magnitudes
J ≤ 9. Based on both the color-magnitude distribution, and the fact that most lie relatively close
to the Galactic plane, we discuss these sources separately.
60
Cross-referencing against SIMBAD, using the 2MASS positions, leads to positive identifications
for 386 sources, as follows:
• One hundred seventeen sources are within 10–1500 of a source from the IRAS catalog. These
are likely to be dusty giants, asymptotic giant branch (AGB) stars, supergiants or young
protostars. Again, most lie close to the Plane.
• One hundred thirty eight sources lie within 2–300 of stars cataloged in the Henry Draper,
Bonner Durchmusterung, Cape Durchmusterung, Cape Photographic Durchmusterung, Guide
Star Catalog, or PPM catalog. None of these stars have significant proper motions, and the
near-infrared and optical/infrared colors are consistent with red giant or AGB stars.
• Thirteen stars are classified in SIMBAD as carbon stars. Again, all lie on the AGB.
• Eighty stars are identified as Miras and sixteen stars are classed as semi-regular variables;
both datasets are predominantly M-type AGB long-period variables. These stars show a
strong concentration towards the Plane and the Bulge.
• Eighteen sources are identified with a variety of late-type stars, including red giant variables,
symbiotic stars, pre-main sequence variables and a symbiotic star.
• Finally, four sources are matched to known M-dwarf proper motion stars. We discuss these
further below.
Near-IR color-magnitude diagrams of these sources are shown in the Appendix.
Two hundred and two bright ultracool candidates have no previous identification listed in the
SIMBAD database. However, all save two of those sources have optical counterparts (positional
offset of less than 500 from the USNOA-1.0 catalog listed in the 2MASS database. Since the USNO
catalog is based on scans of the POSS I O/E plates in the North (average epoch ∼1953) and the
SERC/UKST J and ESO R plates in the South (average epoch ∼ 1979), this indicates that these
sources have proper motions of less than 0.00 1 yr−1 and 0.00 2 yr−1 , respectively—indeed, in every
case the measured offsets indicate negligible relative motion (USNO/2MASS). Both sources which
lack cataloged USNOA-1.0 counterparts are clearly visible at the 2MASS position on second-epoch
UKST IIIaF plates taken in the mid-1980s, also indicating low proper motions.
The presence of non-moving optical counterparts strongly suggests that all of these uncataloged
sources are likely to be distant reddened stars or red giants, rather than nearby dwarfs. Confirmation
of this hypothesis comes from the (R − J)/(J − KS ) two-color diagram (Figure 3.5), which shows
that the overwhelming majority have significantly bluer (R − J) colors than expected for late-M
or L dwarfs. Given the low Galactic latitude of most sources, the potential exists for mismatches.
However, as discussed in more detail in the Appendix, spectroscopy of the relatively small number
61
of sources with near-infrared colors consistent with late-M/L dwarfs shows that none are late-type
dwarfs.
In summary, only four sources among the 588 ultracool candidates with J ≤ 9 are likely to be
genuine nearby late-type dwarfs. These stars are as follows:
G 180-11: This object is included in the third Catalog of Nearby Stars (Gliese & Jahreiß 1991,
pCNS3). Reid, Hawley, & Gizis (1995) measure a spectral type of M4.5 and estimate a distance
of 13±3.9 pc. (MV = 13.11). McCarthy, Zuckerman & Becklin (2001) identify a candidate
companion, with I = 12.6 and a separation of 1.00 5 at PA=266◦ . There is no object at the
appropriate location on the POSS I image of this field, suggesting that the fainter object
is associated with G 180-11. If the companion were a late-type dwarf, then the absolute
magnitude (MI ∼ 12) implies a spectral type of ∼M6 and KS ∼ 10, ∼ 2 magnitudes fainter
than the primary. There is no evidence for significant distortion in the 2MASS point-spread
function, but that might reflect the large pixel scale (1.00 5) and consequent poor sampling.
Alternatively, the hypothesized companion might be a white dwarf, in which case the inferred
absolute magnitude would be consistent with Tef f ∼ 11, 000 K and an expected apparent
magnitude of J ∼ 12.5. Further observations are required to decide between these hypotheses.
G 139-3: This is also a star included in the pCNS3. The spectral type is M4 (Reid, Hawley, &
Gizis 1995), and the spectroscopic parallax gives a distance of 13.8±4.0 pc (MV = 12.49).
BD-01 3925D: This object is a wide companion of the K0 dwarf, BD -1:3925A or HD 192263,
(π = 50.27 ± 1.13 mas; ESA (1997)). BD-01 3925D is not listed in the pCNS3, but has
MK = 5.61 for d = 19.9 pc, consistent with a spectral type of M0/M1.
EZ Aqr: This object is also known as Gl 866, the well-known triple system (Delfosse et al. 1999).
This system is included in pCNS3, has a spectral type of M5.5, and a distance of 3.4±0.03 pc.
With the possible exception of Gl 866ABC, these dwarfs have a relatively unusual location on
the (J − H)/(H − KS ) diagram. In the 2MASS All-Sky Release (where the photometry for bright
stars is improved over the Second Release), the revised photometry for G 180-11 and G139-3 puts
them blueward of our J − K = 1 cut but the remaining two objects still have unusually red colors.
Since M dwarfs with spectral types earlier than M5 would be expected to have (J − KS ) < 1.0,
further observations of these objects are desirable. Data for these stars are listed in Table 3.6.
3.4
Observations
Follow-up far-red optical spectroscopy has been obtained for 298 potential nearby dwarfs during
five separate observing runs at NOAO facilities2 . (Data for 9 objects were obtained from other
2 Spectra
are available upon request from [email protected].
62
sources.) Tables 3.7–3.13 list the positions (as a 2MASS name), photometry, observation date, and
derived data for all of the observed targets3 .
The first run was at the Kitt Peak 2.1 m with the GoldCam spectrograph on 2000 September
29 through October 2. The majority of the run was dedicated to follow-up of proper-motion selected
candidates (Paper III). We used a 1.00 3 slit and a 400 line mm−1 grating blazed at 8000 Å to give
a resolution of 5.1 Å (2.8 pixels) covering the wavelength range 5500–9300 Å. Higher orders were
blocked using a OG550 filter. Weather was good with 100 –1.00 5 seeing. These data were not flat-fielded
due to problems with fringing (see Paper III for a detailed discussion).
Observations were obtained on the Kitt Peak 4 m on 2001 July 13–23 with the RC Spectrograph
to cover 6000–10000 Å in first order. An OG530 filter was used to block second-order light. We
achieved a resolution of 5.6 Å (2 pixels) with a 316 line mm−1 grating blazed at 7500 Å and a 1.00 5
slit. The run had fair weather with partly cloudy conditions and a wide range of seeing. We were
able to confirm many carbon stars and giants as well as obtain data on brighter targets.
The same instrumental setup was used on 2002 January 21–24 except an OG550 filter was used
to block higher orders. Good weather (seeing 0.00 9–1.00 2) on the first two nights and the fourth night
permitted the use of a 100 slit resulting in a resolution of 4.7 Å (1.7 pixels). The seeing on the third
night ranged from 1.00 5–200 and a 1.00 5 slit was used to obtain a resolution of 5.2 Å (1.9 pixels).
Coincident observing (2002 January 22–25) with the Blanco 4 m on Cerro Tololo also had good
weather with mostly 100 –200 seeing. A Loral 3K CCD and the RC spectrograph with a 315 line mm−1
grating blazed at 7500 Å and a 100 slit was used to cover the range 5500–10000 Å with a resolution
of 5.5 Å (2.8 pixels). An OG515 filter was used to block higher orders.
Immediately following, data were obtained with the CTIO 1.5 m on 2002 January 26–30 with
a Loral 1K CCD and RC Spectrograph to cover 6000–8600 Å. Resolution of 6.5 Å (3 pixels) was
obtained with a 400 line mm−1 grating blazed at 8000 Å and a 1.00 5 slit. The seeing ranged from
0.00 7–200 .
All the spectra were flat-fielded, corrected for bad pixels, extracted, and wavelength- and fluxcalibrated using the standard IRAF packages CCDPROC and DOSLIT. (Data from 2000 September
were not flat-fielded.) Wavelength calibration was determined using HeNeAr arcs taken nightly. The
flux-calibration was done using HD 19445, HD 84937, Ross 640, G 191-B2b, L 1363-3, and Feige 34
(Oke & Gunn 1983; Hamuy et al. 1994).
3.5
Results
We have derived spectral types, absolute magnitudes, and distances for all of the observed
dwarfs. Absolute magnitudes are estimated based on a spectral type/MJ relation; and distance
estimates are made using the derived MJ and 2MASS J-band photometry. Table 3.7 lists the data
3 The 2MASS designation is 2MASSI Jhhmmss[.]s±ddmmss. In addition, we note that the astrometry and photometry for all objects is likely to be different from those listed in the 2MASS All-Sky Release.
63
for forty-seven newly discovered objects that lie within 20 pc and have types M7 and later. These
objects are additions to the core sample that is used for our luminosity and mass function analysis
(see §3.7. Data for 139 ultracool dwarfs that lie outside of 20 pc are listed in Table 3.8. Data for
ten M dwarfs earlier than M7 with a distance estimates less than 20 pc (or within 1σ) are listed
in Table 3.9 while fifty-three more distant objects are listed in Table 3.10. Five objects that have
spectral features indicative of youth are listed in Table 3.11, fifty-four giants and carbon stars/dwarfs
are discussed below and listed in Tables 3.12 and 3.13. Three objects (2MASSI J0150116+152357,
2MASSI J0447575−055324, and 2MASSI J0442007−135623) are reddened, distant, early-type stars.
The color-color and color-magnitude diagrams for the 365 dwarfs present in the portion of the 2MU2
sample presented here are shown in Figure 3.6.
3.5.1
Spectral Types
We found that using our spectral indices (listed in Table 4 of Paper III) as a predictor of
spectral type was unreliable for cool dwarfs. This is especially true for M6–M8 dwarfs since the TiO
5 relation turns around near M7.5 (see Paper III, Figure 3, left panel), leading to highly ambiguous
classifications.
As a result, all spectral types for M dwarfs in this Paper are determined via visual comparison
with standard star spectra taken during the course of our program. Program objects are typed
by being normalized and plotted between spectra from a grid of eight standard M1–M9 dwarfs
(Kirkpatrick, Henry, & McCarthy 1991). L dwarf types are determined via comparison with nine
standard, integer type L0–L8 publicly available LRIS spectra taken as part of the 2MASS Rare
Objects project (Kirkpatrick et al. 1999, 2001). In addition, integer types are favored over halfinteger types. The resulting uncertainty for all types is ±0.5 subtypes, except where noted by a “?”
where low signal-to-noise increases the uncertainty to 1 or 2 types.
3.5.1.1
Giants and Carbon Stars/Dwarfs
In the course of spectroscopic follow-up of potential nearby dwarfs, many targets turned out
to be distant giants or carbon stars. In Table 3.12 we list the photometry, astrometry, and rough
spectral types (±1 type) for the observed giants. The spectral types were estimated by side-by-side
comparison with observed spectral standards from Garcia (1989) and spectra kindly provided by
J.D. Kirkpatrick from Kirkpatrick, Henry, & Irwin (1997). In Table 3.13 we list the photometry
and astrometry for the carbon stars. Two of these are carbon dwarfs with detectable proper motion
between the first epoch sky survey plates and the 2MASS images. These will be discussed in detail
in a future paper (P.J. Lowrance et al., in preparation).
64
3.5.2
Absolute Magnitudes and Distances
MJ and distance estimates for all of the dwarfs in our sample are listed in Tables 3.5–3.10.
Absolute magnitudes for spectral types M2–M5.5 were derived using TiO 5, CaH 2, and CaOH as
described in Paper III (Figure 4). For later types, however, the index relations are double valued.
As a result, we have used spectral type as a predictor of MJ .
Dahn et al. (2002) have shown that MJ is well correlated with spectral type. We have rederived
that relation, supplementing data kindly provided by H. Harris with several early objects from
PMSU and the 8 pc samples. The data used to make the relation are listed in Table 3.14 and are
plotted in Figure 3.7. A fourth order polynomial was found to best fit the data, and is valid for
types M6–L8:
MJ = −4.410 + 5.043(ST ) − 0.6193(ST )2 + 0.03453(ST )3 − 0.0006892(ST )4
(3.6)
where ST=0, 10, 18 for spectral types M0, L0, L8, respectively. The uncertainty in spectral type
dominates the uncertainty in the estimated MJ .
Distances are derived for program objects using the estimated MJ and 2MASS J photometry.
The uncertainties in the derived distances are also dominated by the uncertainty in spectral type.
(The uncertainties in the 2MASS J photometry are typically only 0.02–0.03 magnitudes and, as
stated above, the uncertainty in MJ is mostly due to the uncertainty in spectral type.)
3.6
Interesting Individual Objects
Spectra for many of these objects are shown in Figures 3.8 – 3.10.
3.6.1
L Dwarfs within 10 pc
2M 0423: L7.5 at 9.2 pc. This object is typed as T0 by Geballe et al. (2002) based on the strength
of water absorption and the detection of methane absorption bands in the 1–2.5 µm region.
In addition, Schneider et al. (2002) type this object as L5: based on low-resolution optical
spectra. In general, spectral types based on optical and near infrared spectra agree, but there
are a few cases where they do not. This issue is discussed in Burgasser et al. (2003) and will
be addressed in detail in a future paper (J.D. Kirkpatrick et al., in preparation).
2M 0835: L5 at 8.3 pc. This L dwarf is among the brightest of its type, with J = 13. As such,
it is a good candidate for high resolution observations to check for a possible companion. A
trigonometric parallax measurement would also help to confirm this as a single L dwarf within
10 pc or a multiple system at a slightly larger distance.
65
3.6.2
Brown Dwarfs
Two very nearby L dwarfs in our sample have Li I absorption at 6708 Å confirming their brown
dwarf status.
2M 0652: L4.5 at 11.1 pc with strong lithium absorption feature.
2M 2057: L1.5 at 15.7 pc. This spectrum displays both lithium absorption and Hα emission.
Kelu-1 and the previously mentioned 2M 0423 also both have these features (Ruiz, Leggett, &
Allard (1997) and J.D. Kirkpatrick et al., in preparation).
3.6.3
Active Objects
We observed several objects that had unusually strong Hα emission—we list the equivalent
width (EW) of the line below. The activity level of the entire sample will be discussed in a future
paper (J. Liebert et al., in preparation).
LP 423- 31/2M 0752: This M7 (at 10.5 pc) was observed three times during our program: twice
in 2002 January and once during a run dedicated to NLTT follow-up in 2001 November. On
all occasions, the emission strength was very strong with the EW ranging from 33–45 Å.
2M 1707: Emission in L dwarfs is not common—only two presented here display it. This L0.5
(at 26 pc) has significant Hα with EW=35 Å and this object should be monitored to check
whether we happened to observe during a period of unusually high activity. A spectrum of
this object is shown in Figure 3.8.
2M 2057: This brown dwarf with Hα emission is discussed in § 3.6.2 above.
2M 2351: This M7 at 35 pc displayed a strong Hα
2M 0435: In addition to weak CaH absorption, this object displays weak emission in Hα, K I and
Na I. It is about one magnitude brighter than the two TW Hya candidates (Gizis 2002) and
is probably within 30 pc. It is in the direction of the nearby star forming region MBM 20;
however, a current estimate of the distance to this cloud puts it between 112 and 161 pc—
significantly more distant than our estimate for this object (Sandell, Reipurth, & Gahm 1987;
Hearty et al. 2000).
2M 0608: This dwarf also shows enhanced VO absorption (7334–7534 and 7851–7973 Å) which is
another characteristic of young late-type objects (J.D Kirkpatrick et al., in preparation). It is
also fairly near on the sky to 2M 0619 as discussed below.
2M 0619: This object displays the characteristics of a young dwarf. In addition, this object and
2M 0608 are close to each other on the sky and lie fairly close to the plane. However, rough
distance estimates of 30 pc for 2M 0608 and 100 pc for 2M 0619 suggest that they are not
actually associated.
2M 2234: This dwarf also displays strong Hα emission consistent with it being a young, active
object.
3.6.5
Two Blue L Dwarfs
There are two L dwarfs which have unusually blue colors and can easily be seen as outliers in
Figure 3.6. One of these objects, 2MASS J1300425+191235 (L1, 14 pc), was originally discovered by
Gizis et al. (2000) and its data are listed in Table 3.5. The other object, 2MASS J172139+334415
(L3, 15 pc) was discovered as a part of this program and its data are listed in Table 3.7.
Both of these objects have significant proper motion. Based on POSS plates measurements, we
find (µα , µδ ) = −0.7, −1.100 yr−1 for 2M 1300 and (µα , µδ ) = −1.6, 0.600 yr−1 for 2M 1721. Gizis et
al. (2000) also pointed out 2M 1300’s unusual colors and high velocity and suggested that it is likely
to be old. The large proper motion of 2M 1712 supports their claim, however, we plan to obtain
near-infrared spectroscopic observations of these two objects to find out which spectral features are
causing the anomalous colors.
3.6.6
LP 775-31 & LP 655-48
Recently, McCaughrean, Scholz, & Lodieu (2002) pointed out that these two objects (aka
2MASSI 0435161−160657 and 2MASSI 0440232−053008) were mistyped in Paper III and that a
retyping places them within 10 pc. While we agree that these objects are cooler than M6 as we
previously stated, we find them both to be spectral type M7 (not M7.5 and M8 as in McCaughrean
et al.), which puts them at 8.6 and 9.8 pc respectively. Clearly, trigonometric parallaxes are required
to determine unambiguous distances to these nearby dwarfs.
67
3.7
Sample Characteristics and Preliminary Luminosity
Function4
In this Paper we present new data on almost 300 objects. These data, combined with the
previously known objects, represent 66% of the ultracool candidates in the 2MU2 sample. The
color-magnitude and color-color diagrams for those data are shown in Figure 3.6. In this section, we
point out some of the characteristics of the completed portion of the 2MU2 sample that are relevant
to the study of nearby low-mass stars and brown dwarfs4 .
The upper panel of Figure 3.11 shows the spectral type distribution of the portion of the 2MU2
sample presented here, separately identifying our new discoveries and previously known ultracool
dwarfs. We have at least doubled the number of objects in most spectral type bins, and tripled
it in others. Not until L5 does the number of previously known objects outnumber our additions.
Currently, the follow-up work is the most incomplete for the faintest objects in the sample which is
where we expect to find the coolest, faintest objects, which have the latest spectral types.
The distance distribution of the M7–L8 objects presented here is shown in the middle panel
of Figure 3.11. While we have not discovered any objects within five parsecs, we have doubled the
number of late-type dwarfs in every other distance bin out to 40 pc. In addition, the number of
objects found scales consistently with the increase in volume out to the 20 pc bin. The volume
increases 3.4 times from 10 to 15 pc and the number of objects we have found increases 3.2 times.
Similarly, from 15-20 pc, the volume increases by a factor of 2.4 and the number of objects included
increases by 2.3. This suggests that we are indeed nearly complete out to 20 pc.
In the bottom panel of Figure 3.11, we show spectral type versus distance. Our current sample
includes objects well beyond the 20 pc limit even at spectral types later than L6. This further supports that, once we have complete observations of the full sample including the faintest candidates,
we will have identified a complete sample of late-M and L0–L8 dwarfs within 20 pc of the Sun.
Preliminary field luminosity functions in MJ and MKS (based on the first results from our
2MU2 sample which has a distance limit of 20 pc and an effective sky coverage of 40%) are shown
in the top two panels of Figure 3.12. The components of known binaries are counted separately.
MJ is estimated using our spectral type/MJ relation described in § 3.5.2 or using 2MASS J band
photometry and a trigonometric distance estimate if available. MKS estimates are obtained by
subtracting the 2MASS J − KS color from MJ .
The faintest bins (MJ > 14, MKS > 12.5) should be regarded as substantially incomplete.
The number of objects falls off at magnitudes fainter than MJ = 11 (MKS = 10.5) as these bins
are dominated by evolving brown dwarfs rather than stable stars. While stars remain at a given
magnitude for billions of years, brown dwarfs gradually cool to fainter and fainter magnitudes thus
depleting the brighter magnitude bins.
4 The analysis presented in this section is only for a portion of the sample; the entire sample is discussed in the
following Chapter
68
The peak at MJ = 13.75 with 9 objects is not readily explained. Since we are incomplete at these
faint magnitudes (MJ > 13.5) and the number of objects in these bins will only go up with increased
completeness, it is possible that the peak is not an isolated bump, but rather represents a change to
an increasing slope or a plateau of the luminosity function for MJ > 13.5. This could be explained
as a population of old, massive br12(oc3e)-421d(w)27arfse
hwe oolvmd—nessentialnly83(d,)-403(tist)4237opopulation
that
h
wer imen
3.8
Conclusions
We have described our project to create a statistically robust, volume-limited survey for ultracool dwarfs (spectral types M7–L8). Our goal is to determine the infrared luminosity function
and constrain the mass function of late-type stars and brown dwarfs. We have presented our initial
findings—the discovery of 186 new late-M and L dwarfs. Forty-seven of these are additions to the
20 pc nearby star census of ultracool dwarfs, including two confirmed brown dwarfs. These data,
combined with previously known nearby objects, are a significant step towards estimating the mass
distribution of ultracool field dwarfs. Our future work, especially with the addition of the coolest
objects, will illuminate even further the statistical properties of low-mass stars and brown dwarfs in
the Solar neighborhood.
70
5
10
10
J
MJ + 1.51
5
15
15
0.0
0.5
1.0
(J−KS)
1.5
2.0
0.0
0.5
1.0
(J−KS)
1.5
2.0
Figure 3.1.— Color-magnitude diagram for low-mass stars with trigonometric parallax measurements
shifted to 20 pc (left panel ) and a typical 1◦ 2MASS field (right panel ) with our selection criteria.
Triangles are from the 8 pc sample. Data for ultracool dwarfs (M7–L8, filled circles) and T dwarfs
(filled five-point stars) are from Dahn et al. (2002). Targets are selected if they lie above and to the
right of the cuts.
71
1.0
1.0
(J−H)
1.5
(J−H)
1.5
0.5
0.5
0.0
0.0
-0.2
0.0
0.2
0.4
0.6
(H−KS)
0.8
1.0
1.2
-0.2
0.0
0.2
0.4
0.6
(H−KS)
0.8
1.0
1.2
Figure 3.2.— Color-color diagram for the same data (plotted with the same symbols) as Figure 1 and
our selection criteria. In addition to objects with trigonometric parallax data, we show L dwarfs from
Kirkpatrick et al. (1999, 2000) with uncertainties less than 0.1 mag (crosses) and giants (squares).
We also show the dwarf and giant sequences (both from Bessell & Brett (1988), transformed to the
2MASS system). Targets are selected if they lie within the enclosed region. The region where bright
objects (J < 10) are eliminated as giants is enclosed by a dotted line.
72
Figure 3.3.— Color-magnitude diagram for GKM dwarfs (crosses) and L dwarfs (circles) with known
parallaxes and shifted to 20 pc. The solid line shows the cuts. Objects are selected if they lie above
the solid line.
73
2.0
6
8
1.5
J
(J−H)
10
12
1.0
14
16
0.5
18
1.0
1.5
2.0
(J−KS)
2.5
3.0
0.2
0.4
0.6
0.8
(H−KS)
1.0
1.2
Figure 3.4.— Color-magnitude and color-color diagrams for the targets that survived the cuts described in § 3.3.0.1. Objects fainter than J = 9 are candidates for spectroscopic follow-up. The
population of objects with J ≤ 9 are discussed in § 3.3.2.
74
Figure 3.5.— The (R − J)/(J − KS ) distribution for main-sequence FGKM stars (crosses), L dwarfs
(circles) and bright ultracool candidates with no counterpart listed by SIMBAD (triangles).
75
6
1.4
8
1.2
J
(J−H)
10
12
1.0
0.8
14
0.6
16
1.0
1.5
(J−KS)
2.0
0.4
0.2
2.5
0.4
0.6
(H−KS)
0.8
1.0
Figure 3.6.— Color-magnitude and color-color diagrams for the all of the cool dwarfs present in this
paper. Shown are early and mid-M dwarfs (M0–M6.5, plus signs), late-type M dwarfs (M7–M9.5,
triangles), and L dwarfs (circles). The two blue L dwarf outliers are discussed in § 3.6.5
76
9
10
11
MJ
12
13
14
15
16
M4
M6
M8
L0
L2
L4
Spectral Type
L6
L8
Figure 3.7.— MJ /spectral type calibration. Our fourth-order fit to the data (solid line) is shown,
as is the linear fit found by Dahn et al. (2002) (dashed line) to a similar dataset. Data plotted are
listed in Table 3.14
77
Figure 3.8.— Spectra for some of the interesting objects. Each object is discussed in § 3.6. The
bottom spectrum is not offset and the zero point for each offset spectrum is shown by a dashed line.
78
Figure 3.9.— Spectra for candidate young objects and the M6 and M7 spectral standards LHS 1326
and VB 8. The spectral features of each object are discussed in §3.6.4. The bottom spectrum is not
offset and the zero point for each offset spectrum is shown by a dashed line.
79
Figure 3.10.— Spectra of 2M 0608 and the M9 standard LHS 2065. This object is discussed in
§3.6.4. The bottom spectrum is not offset and the zero point of the offset spectrum is shown by a
dashed line.
80
80
70
Number of Objects
60
50
40
30
20
10
0
M6
M8
L0
L2
L4
L6
L8
Spectral Type Bin
60
50
Number of Objects
40
30
20
10
0
0-5
5-10
10-15
15-20
20-25
25-30
30-35
35-40
40-45
45-50
Distance Bin (pc)
80
70
Distance (pc)
60
50
40
30
20
10
0
M5
M6
M7
M8
M9
L0
L1
L2
L3
L4
L5
L6
L7
L8
Spectral Type
Figure 3.11.— Stacked histogram of the spectral type of all the dwarfs M5 and later in our sample
(top) and distance distributions of the M7–L8 dwarfs (middle). Darkly shaded region indicates
objects previously known while the lightly shaded region represents additions. The bottom panel
shows spectral type versus distance for dwarfs later than M5. Shown are new objects (circles) and
previously known objects (triangles), and our distance limit (horizontal line). Multiplicity has been
ignored in all three plots.
81
30
Number of Objects
25
20
15
10
5
0
10.75 11.25 11.75 12.25 12.75 13.25 13.75 14.25 14.75
MJ
30
Number of Objects
25
20
15
10
5
0
9.75
10.25
10.75
11.25
11.75
MK
12.25
12.75
13.25
25
Number of Objects
20
15
10
5
0
M7
M8
M9
L0
L1 L2 L3 L4
Spectral Type Bin
L5
L6
L7
L8
Figure 3.12.— Preliminary field luminosity function (top), and spectral type distribution (bottom) for
dwarfs within 20 pc. Hatched region indicates objects with trigonometric parallaxes while shading
indicates MJ is based on spectral type. MJ bins are 0.5 mags wide and are labeled with the centroid.
Spectral type bins contain both the integer type and the 0.5 class cooler subtype. Multiplicity has
been taken into account and the magnitudes corrected.
82
10
10
12
12
J
8
J
8
14
14
16
16
18
18
1.0
1.5
2.0
(J−KS)
2.5
3.0
L0
L2
L4
L6
Spectral Type
L8
Figure 3.13.— Color-magnitude for the all of the targets in the sample that are not presented here
(left) and J versus spectral type for all 250 objects listed in the L Dwarf Archive (right). Shown
are objects for which we have data (plus signs) and objects that still require follow-up observations
(circles). The dashed line shows where our current incompleteness becomes significant and the solid
line marks the 20 pc limit.
83
Table 3.2.
Region
Cataloged Clouds
lmin
lmax
Cepheus
Per OB2
Taurus
Orion B
Orion A
Mon R2
Cham
Lupus
100
154
163
202.5
210
210
295
½ 333
350
ρ Oph
350
Upper Sco ½ 355
4
R CrA
352
120
163
202.5
210
218
218
305
350
2
13
363
15
4
bmin
11
−25
−22
−21
−21
−14
−20
10
13
10
16
−15
−22
bmax
22
−10
−10
−10
−14
−10
−12
22
24
19
27
−10
−20
Note. — These regions have been eliminated
from the sample. The positions have been expanded upon from regions listed by Dame et
al. (1987) and Dutra & Bica (2002). Some of
the regions overlap.
85
Table 3.3. Uncataloged Reddening Regions
lmin
0
150
180
199
308
lmax
bmin
96
180
360
214
310
−16
10
−13
−13
13
bmax
16
13
13
−27
16
Note. — Objects lying in
these regions have been removed
from the sample.
86
Table 3.4.
Accounting of Steps to Refine J > 9 Portion of the 2MU2 Sample
Item
Number
Faint Candidates
(F − J)/(J − K)
Visual Inspection
SIMBAD
Clouds
Bland
Ultracool Candidates
1084
137
211
24
41
34
637
Note. — Similar to Table 3.1 except listing the cuts applied only to the
fainter (J > 9) portion of the sample and their contribution to reduce the
number of ultracool candidates to 637.
87
88
1029216+162652
1035245+250745
1047126+402643
1047310−181557
1049414+253852
1058478−154817∗
1108307+683017∗
1112256+354813
1121492−131308∗∗
1127534+741107
1146344+223052
0909575−065818
0928397−160312
0952219−192431∗
1016347+275149∗
1024099+181553∗
0820299+450031
0825196+211552∗
0829066+145622
0832045−012835
0840297+182409
0850359+105715
0853362−032932∗
0354013+231633
0409095+210439
0740096+321203
0741068+173845∗
0746425+200032∗∗
0810586+142039∗
0818580+233352∗
0337036−175807
0339352−352544∗
0350573+181806
0351000−005244∗
0024246−015819∗
0024442−270825
0027559+221932∗
0030300−145033
0051107−154417
0052546−270559
0058425−065123
0103320+193536
0104376+145724
0105190+140740
0127391+280553
0145452+130600
0149089+295613
0205034+125142
0205293−115930∗∗
0208183+254253
0208236+273740
0220181+241804
0240295+283257
0248410−165121∗
0253202+271333∗
0255035−470050∗
0320596+185423∗
2MASSI
Designation
Gl 417B
LHS 2397a/LP 732- 94
DENIS-P J1058−1548
LP 213- 67
DENIS-P J1047−1815
LHS 2243/LP 315- 53
LHS 2065/LP 666- 9
DENIS-P J0909−0658
LHS 2034/LP 425-140
LHS 1937/LP 423- 14
LP 944- 20/BRI 0337−3535
LP 413- 53
LHS 1604/LP 593- 68
DENIS-P J0255−4700
LP 412- 31
LP 771- 21/BR 0246−1703
DENIS-P J0205.4−1159
CTI 012657.5+280202
LHS 1294/LP 468-199
RG 0050.5−2722
BRI 0021−0214
LHS 1070/LP 881- 64
LP 349- 25
Other
Names
Table 3.5.
11.860a
9.262
10.608
16.792
15.230
13.611
14.320
16.264
13.696
13.588
14.018
12.783
13.443
15.680
14.581
14.015
15.701
13.008
12.679
12.557
12.504
13.225
11.744
15.594
10.748
12.951
11.262
13.122
15.545
16.167
11.995
11.742
12.714
12.137
16.294
15.116
14.716
14.127
11.052
16.460
11.185
13.897
15.337
11.877
11.951
12.242
14.307
14.700
11.417
14.196
12.398
14.184
13.139
14.573
11.929
13.059
14.166
J
0.740
0.730
0.638
1.437
1.082
0.617
0.875
1.383
0.672
0.665
0.680
0.695
0.852
1.234
0.991
0.905
1.154
0.686
0.701
0.701
0.667
1.036
0.701
1.182
0.731
0.729
0.670
0.704
1.084
1.330
0.633
0.743
0.669
0.635
1.295
1.328
0.926
0.818
0.647
1.234
0.717
0.810
1.036
0.595
0.657
0.664
0.961
0.819
0.640
0.771
0.648
0.944
0.912
1.100
0.672
0.692
0.967
J −H
1.280
1.030
1.047
2.414
1.806
1.072
1.413
2.111
1.088
1.040
1.188
1.028
1.434
2.022
1.599
1.436
1.833
1.096
1.103
1.148
1.049
1.698
1.172
2.006
1.223
1.188
1.071
1.147
1.703
1.984
1.026
1.255
1.104
1.007
2.060
2.071
1.599
1.440
1.003
1.999
1.213
1.350
1.700
1.031
1.005
1.037
1.701
1.420
1.017
1.299
1.004
1.673
1.539
1.879
1.206
1.088
1.525
J − KS
M8.5
L3
L4.5
M7
L0.5
M9
M7
L5
L7.5
L2
L1.5
M6
L6
M9
L0
L2
M7
M7.5
M7
L2.5
L1
M8
L2.5:
M6
L3
L1
L4.5
M8.5
M8
L3
M9.5
M5.5
M8
L7
L3.5
M8
L0
L6
M8
M7
M8.5
M1.5
M9.5
L5
L7
L1
L5
M6
M7.5
M8
M8
L8
M8
L4.5
M9
M8c
M7.5d
Spectral
Type
11.6±0.1
···
11.2±0.2
14.4±0.2
12.9±0.2
11.2±0.2
11.7±0.1
14.0±0.2
11.2±0.2
10.7±0.3
11.3±0.2
···
11.6±0.1
13.6±0.2
(14.4±0.2)
12.0±0.1
13.6±0.2
10.1±0.4
11.0±0.2
11.2±0.2
11.2±0.2
14.8±0.1
11.2±0.2
13.3±0.2
11.5±0.1
11.2±0.2
11.0±0.2
11.3±0.2
12.7±0.2
13.3±0.2
10.7±0.3
(11.9±0.1)
11.5±0.1
10.7±0.3
13.6±0.2
14.6±0.2
12.3±0.2
12.1±0.2
10.1±0.4
(14.0±0.2)
11.5±0.1
11.7±0.1
12.3±0.2
10.7±0.3
11.0±0.2
10.7±0.3
12.5±0.2
12.0±0.1
(11.2±0.2)f
12.5±0.2
10.1±0.4
12.7±0.2
12.0±0.1
(13.3±0.2)
(11.3±0.2)
(11.2±0.2)
(12.7±0.2)
MJ
11.3±0.7
···
7.80±0.6
29.4±3.4
29.5±3.0
31.0±2.6
33.0±2.1
28.1±3.2
32.2±2.7
37.2±4.4
34.6±2.5
···
23.4±1.5
26.6±3.0
(10.6±1.0)
25.3±1.7
26.9±3.1
37.9±6.5
22.0±2.2
19.1±1.6
18.6±1.5
4.90±0.3
13.1±1.1
28.5±3.2
7.20±0.5
22.9±1.9
11.5±1.1
22.9±1.7
37.5±3.6
37.1±4.3
17.9±2.1
(9.50±0.6)
17.8±1.2
19.1±2.2
35.3±4.2
12.5±1.0
30.3±2.4
24.9±1.8
15.4±2.6
(30.7±3.7)
8.80±0.6
27.1±1.7
40.3±3.2
16.9±2.0
15.8±1.5
20.0±2.4
23.2±2.0
34.7±2.4
(11.3±0.9)f
22.0±1.9
28.6±4.9
20.0±1.9
16.9±1.1
(17.8±1.9)
(13.2±1.0)
(24.0±2.0)
(19.9±1.8)
d
(pc)
π
19.8±0.6
13.10±0.07b
21.7±0.4
14.3±0.4
27.2±0.6
11.99±0.06
17.3±0.3
14.0±0.2
25.6±2.3
8.50±0.1
10.7±0.1
12.21±0.04
12.89±0.06
11.15±0.07g
12.99±0.05
10.32±0.04
14.42±0.23
11.54±0.04
14.97±0.05
11.31±0.03e
14.7±2.9
10.43±0.43
14.5±0.1
5.00±0.1
12.25±0.05
10.94±0.04
16.2±1.4
22.5±0.4
11.51±0.19
32.8±0.5
11.68±0.05
21.6±4.7
11.5±0.5
7.39±0.66
dπ
(pc)
11.44±0.05
11.94±0.47
11.56±0.10
9.92±0.20
MJ
Previously Known Cool Dwarfs Recovered in the 2MU2 Sample
4
7
2
4
6
4
6
4
4
5
3
4
3
4
4
4
3
1
2
π
Ref.
5,6,7
8
2,7
1,3,2
4,2
3,2
3,2
1,2
Mult.
Ref.
1
2
3
4
4
5
4
4
6
6
7
3
8
4
9
4
4
6
6
3
6
10
3
4
3
3
3
6
4
4
3
4
6
6
4
4
4
4
3
8
3
10
4
6
3
6
4
4
3
10
6
9
6
4
3
6
8
Discovery
Ref.
89
2331016−040619
2049197−194432
2113029−100940
2140293+162518
2147436+143131
2202112−110945
2206228−204705
2206449−421720
2224438−015852∗
2234139+235955
2235490+184029
2255584+282246
2306292−050227∗
1543581+320641
1546054+374946∗
1551066+645704
1553199+140033
1615441+355900
1627279+810507
1635191+422305
1658037+702701∗
1726000+153819
1728114+394859
1733189+463359
1750129+442404
1757154+704201∗
1843221+404021∗
1411175+393636
1426316+155701
1430378+594325
1448033+155414
1456383−280947∗
1457396+451716
1500342−005944
1506544+132106∗
1507476−162738∗
1311391+803222
1338261+414034
1343167+394508
1403223+300754∗
1200329+204851
1224522−123835∗
1228152−154734
1237270−211748
1239272+551537
1246467+402715
1246517+314811
1253124+403403∗
1300425+191235∗
1305401−254106∗
2MASSI
Designation
LP 460- 44
LP 345- 18
LP 759- 17/DENIS-P J2202−1109
LP 44-162
LHS 3406/LP 229- 30
LP 328- 36
TVLM 868-54745
LHS 2930/LP 98- 79
LHS 2980/LP 441- 17
LHS 3003/LP 914- 54
Kelu-1
LHS 2632/LP 321-222
LHS 2645/LP 218- 8
BR 1222−1221
DENIS-P J1228−1547
Other
Names
12.850
12.564
14.375
12.665
14.670
15.002
12.255
12.177
12.710
13.417
12.814
14.217
16.177
12.691
14.679
12.868
10.765
12.481
9.957
13.145
12.639
13.414
12.822
12.731
12.437
12.870
13.019
14.571
13.042
12.886
13.309
15.653
15.964
13.214
12.791
11.446
11.299
12.871
12.863
12.943
13.842
12.364
12.381
15.569
14.052
13.176
12.458
12.554
11.372
12.937
J
0.605
0.733
1.012
0.616
1.131
1.025
0.667
0.620
0.641
1.030
0.671
0.913
1.325
0.683
0.867
0.686
0.646
0.629
0.630
0.733
0.656
1.002
0.920
0.615
0.644
0.721
0.750
1.020
0.710
0.676
0.766
1.193
1.183
0.806
0.622
0.604
0.632
0.635
0.642
0.673
0.708
0.650
0.677
1.091
1.249
0.823
0.632
0.619
0.654
0.648
J −H
1.026
1.193
1.570
1.020
1.927
1.699
1.022
1.004
1.105
1.691
1.100
1.466
2.066
1.065
1.405
1.159
1.009
1.010
1.040
1.222
1.018
1.666
1.520
1.004
1.018
1.135
1.172
1.630
1.168
1.086
1.390
2.017
2.066
1.357
1.031
1.073
1.030
1.106
1.049
1.164
1.190
1.007
1.056
1.974
2.035
1.341
1.125
1.016
1.084
1.007
J − KS
M7.5
M6
M8.5
M8
M6.5
M8
L2
L4.5
M9.5
M7
M6
M7.5
M8
L3
L5
M6.5
M7.5
M8.5
M9
L3
M9
M8
L1
L2
L7
M9.5
M7.5
M7.5
M8l
M7
M9
L5
M6
L5
L4
M6.5
M7.5
L1
L2
M8
L2.5
L5
M8.5
L1.5
M9
M6.5
M6.5
M7
M9
Spectral
Type
26.5±3.1
16.6±1.1
(14.6±1.6)
32.3±5.6
(16.7±1.8)h
24.1±2.5
22.9±3.3
17.5±1.7
13.9±0.9
16.7±1.3
(21.5±1.8)
22.2±1.9
33.5±3.8
18.8±1.4
32.1±2.4
(19.1±1.3)i
11.5±1.6
25.4±3.5
7.00±0.8
21.7±1.4
31.3±9.8j
14.1±1.3
7.10±0.8
28.5±4.0
19.7±1.9
20.4±1.5
20.5±1.3
24.0±2.2
20.7±1.4
22.2±1.8
18.3±1.2
46.6±3.9
(20.1±1.9)k
21.0±1.3
(23.2±2.3)
12.5±1.2
10.7±0.9
24.1±2.3
35.4±6.1
(21.1±1.5)
(34.5±2.9)
24.1±3.4
(17.6±1.5)m
44.9±3.8
14.0±1.5
20.7±1.3
22.1±2.6
30.7±5.3
12.1±1.2
(22.7±1.9)
12.3±0.2
13.3±0.2
11.6±0.1
10.7±0.3
10.1±0.4
11.0±0.2
(11.2±0.2)
d
(pc)
10.7±0.3
11.5±0.1
(13.5±0.2)
10.1±0.4
(13.6±0.2)h
13.1±0.2
10.5±0.3
11.0±0.2
12.0±0.1
12.3±0.2
(11.2±0.2)
12.5±0.2
13.6±0.2
11.3±0.2
12.1±0.2
(11.5±0.1)i
10.5±0.3
10.5±0.3
10.7±0.3
11.5±0.1
10.2±0.7j
12.7±0.2
13.6±0.2
10.5±0.3
11.0±0.2
11.3±0.2
11.5±0.1
12.7±0.2
11.5±0.1
11.2±0.2
12.0±0.1
12.3±0.2
(14.4±0.2)k
11.6±0.1
(11.0±0.2)
11.0±0.2
11.2±0.2
11.0±0.2
10.1±0.4
(11.3±0.2)
(11.2±0.2)
10.5±0.3
(11.2±0.2)m
MJ
Table 3.5 (cont’d)
π
13.77±0.04
10.55±0.04
11.96±0.04
11.4±0.1
14.1±0.2
18.6±0.2
7.33±0.03
6.30±0.2
10.96±0.08
13.50±0.03
9.60±0.1
18.7±0.7
17.1±1.1
20.2±0.8
dπ
(pc)
10.85±0.04
12.06±0.09
11.40±0.14
12.85±0.09
MJ
4
6
4
4
3
6
4
3
4
π
Ref.
11,2,7
11,2,7
11,2,7
7,6
2
7,6
10,11,2,7
2,7
7,6
9,1,2
Mult.
Ref.
6
11
9
6
4
4
3
3
6
12
6
4
4
6
4
6
3
3
3
6
11
6
4
3
6
6
6
4
6
6
6
4
4
6
6
3
3
6
6
6
6
3
6
4
4
6
3
3
6
6
Discovery
Ref.
90
LP 523- 55
LP 348- 11
LP 402- 58
Other
Names
12.769
12.761
13.186
12.615
12.759
J
0.695
0.660
0.734
0.663
0.681
J −H
1.128
1.053
1.191
1.053
1.060
J − KS
M8
M7
M9
M8
M6
Spectral
Type
11.2±0.2
10.7±0.3
11.5±0.1
11.2±0.2
10.1±0.4
MJ
21.0±1.8
25.4±3.0
22.1±1.5
19.6±1.6
33.8±5.8
d
(pc)
MJ
π
dπ
(pc)
π
Ref.
Mult.
Ref.
6
3
6
3
3
Discovery
Ref.
MJ = 13.85 for both components.
References. — Discovery (1) Irwin, McMahon, & Reid (1991); (2) McCarthy, Bertiau, & Treanor (1964); (3) NLTT; (4) Kirkpatrick
et al. (2000); (5) Reid & Gilmore (1981); (6) Gizis et al. (2000); (7) Kirkpatrick et al. (1994); (8) Kirkpatrick et al. (1999); (9) Delfosse
et al. (1997); (10) Martı́n et al. (1999); (11) Tinney, Mould, & Reid (1993); (12) Ruiz, Leggett, & Allard (1997)
References. — Multiplicity (1) Koerner et al. (1999); (2) Close et al. (2003); (3) Reid et al. (2001); (4) Gizis et al. (2000); (5)
Kirkpatrick et al. (2001); (6) Bouy et al. (2003); (7) Gizis et al. (2003); (8) Freed, Close, & Siegler (2003); (9) Martı́n, Brandner, &
Basri (1999) (10) Close et al. (2002a); (11) Close et al. (2002b)
References. — Trigonometric Parallax (1) Tinney, Reid, Gizis, & Mould (1995); (2) van Altena, Lee, & Hoffleit (1995) (3) Tinney
(1996); (4) Dahn et al. (2002); (5) Gliese & Jahreiß (1991); (6) Monet et al. (1992); (7) ESA (1997)
MJ = 11.16 and 11.33 (Close et al. 2003). d = 24.4 pc.
ST change from M5.5 in PMSU.
m
l
MJ = 14.45 and 15.10 (Bouy et al. 2003). d = 25.4 pc.
Based on photometric distance found by Tinney, Mould, & Reid (1993).
k
j
MJ = 13.55 and 13.95 (Bouy et al. 2003). d = 21.8 pc.
MJ = 11.32 and 12.10 (Close et al. 2003). d = 24.9 pc.
i
MJ = 11.09 and 14.92 (Freed, Close, & Siegler 2003).
h
MJ = 11.16 and 12.01 (Close et al. 2003). d = 21.8 pc.
g
f
ST change from M6 in PMSU.
MJ = 11.80 and 12.40 (Close et al. 2003).
e
d
ST change from M8 in (Gizis et al. 2000).
b
c
Photometry listed is from Dahn et al. (2002) as the 2MASS photometry is contaminated by a meteor.
a
Note. — MJ and distances listed are estimates obtained using our calibration while MJπ and dπ are based on trigonometric parallax
data. Objects included in our preliminary luminosity function (ST ≥ M7 and d ≤ 20pc) are marked with *; binaries are marked with **.
For multiple systems, the MJ and distance estimate (marked with parentheses) are based on the system’s combined spectral type and
photometry. A revised MJ and distance estimate correcting for multiplicity is given in a footnote for systems with a formal estimate
of d < 20 pc. For multiple systems with a trigonometric parallax measurement, the combined photometry is listed in MJπ and the
component photometry is given in a footnote.
2358290+270205
2334394+193304
2336439+215338
2347367+270206
2349489+122438∗
2MASSI
Designation
Table 3.5 (cont’d)
92
0019262+461407
0019457+521317
0109511−034326
0141032+180450
0144353−071614
0148386−302439
0213288+444445
0251148−035245
0331302−304238
0417374−080000
0423485−041403
0429184−312356
0435161−160657
0439010−235308
0440232−053008
0443376+000205
0445538−304820
0517376−334902
0523382−140302
0652307+471034
0752239+161215
0835425−081923
0847287−153237
0859254−194926
0908380+503208
1006319−165326
1010148−040649
1045240−014957
1104012+195921
1124048+380805
1213033−043243
2MASSI
Designation
SDSS J1045−0149
LP 789- 23
LP 423- 31
LP 655- 48
SDSS 0443+0002
LP 775- 31
SDSS J0423−0414
LP 888- 18
LP 647- 13
Other
Names
12.609
12.820
11.695
13.822
14.187
12.282
13.512
13.082
11.371
12.166
14.452
10.887
10.396
14.413
10.681
12.517
13.409
11.995
13.117
13.545
10.831
13.149
13.519
15.505
14.564
12.041
15.503
13.129
14.462
12.710
14.672
J
0.676
0.748
0.774
0.772
1.183
0.641
0.740
0.821
0.672
0.654
1.010
0.680
0.616
1.045
0.696
0.713
0.835
0.672
0.896
1.175
0.639
1.195
0.892
1.067
1.098
0.620
1.108
0.759
0.984
0.682
0.995
J −H
Table 3.7.
1.135
1.204
1.277
1.315
1.904
1.038
1.269
1.429
1.095
1.112
1.516
1.086
1.060
1.606
1.124
1.350
1.425
1.176
1.486
1.858
1.012
1.993
1.465
1.778
1.646
1.041
1.908
1.319
1.486
1.138
1.669
J − KS
2000
2000
2000
···
2002
2002
2001
2002
2000
2002
2002
2002
2000
2002
2000
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
Jan 24
Jan 28
Jul 23
Jan 23
Sep 30
Jan 27
Jan 25
Jan 27
Sep 30
Jan 26
Sep 29
Jan 28
Jan 25
Jan 25
Jan 24
Jan 22
Jan 23
Jan 24
Jan 23
Jan 24
Jan 22
Jan 26
Jan 23
Jan 31
Jan 22
Jan 25
Jan 24
Oct 02
Oct 02
Sep 29
Obs.
Date
KP 2.1m
KP 2.1m
KP 2.1m
···
CT 4m
CT 1.5m
KP 4m
CT 4m
KP 2.1m
CT 1.5m
CT 4m
CT 1.5m
KP 2.1m
CT 4m
KP 2.1m
CT 1.5m
CT 4m
CT 4m
CT 4m
KP 4m
KP 4m
CT 4m
CT 4m
CT 4m
KP 4m
CT 4m
CT 4m
CT 1.5m
KP 4m
KP 4m
CT 4m
Telescope
M8
M9
M9
L4.5a
L5
M7.5
L1.5
L3
M7.5b
M7.5
L7.5c
M7.5
M7e
L6.5
M7
M9.5
L2
M8
L2.5
L4.5f
M7g
L5
L2
L6?h
L5
M7.5
L6
L1
L4
M8.5
L5
Spectral
Type
M7–L8 Dwarfs Discovered Within 20 pc
d
(pc)
Other
Ref.
11.2±0.2
19.5±1.6
11.5±0.1
18.7±1.2
11.5±0.1
11.1±0.7
1
13.3±0.5
12.6±2.7
2
13.6±0.2
13.4±1.5
3,4
11.0±0.2
18.4±1.8
12.1±0.2
18.7±1.4
12.7±0.2
12.1±1.1
2
11.0±0.2
12.1±1.2
1
11.0±0.2
17.4±1.7
14.6±0.3
9.2±1.4
5,6,7,4
(11.0±0.2)d (9.7±0.9)d
10.7±0.3
8.6±1.0
1,8
14.2±0.2
10.8±1.1
10.7±0.3
9.8±1.1
1,8,9
11.6±0.1
15.3±1.0
7,2
12.3±0.2
16.6±1.3
11.2±0.2
14.7±1.2
9
12.5±0.2
13.4±1.1
2
13.3±0.2
11.1±1.2
10.7±0.3
10.5±1.2
13.6±0.2
8.3±0.9
12.3±0.2
17.5±1.4
14.0±0.9
19.8±8.3
13.6±0.2
15.9±1.8
11.0±0.2
16.4±1.6
9
14.0±0.2
19.8±2.2
12.0±0.1
16.8±1.1
7,10
13.1±0.2
18.8±2.0
11.3±0.2
19.0±1.4
13.6±0.2
16.7±1.8
MJ
CE 303
SDSS 1326−0038
1309218−233035
1326298−003831
1332244−044112
1356414+434258
1411213−211950
1438082+640836
LP 220- 13
Other
Names
2MASSI
Designation
11.769
16.110
12.342
11.704
12.442
12.923
J
0.682
1.066
0.591
0.673
0.619
0.895
J −H
Obs.
Date
Telescope
Spectral
Type
1.103
2002 Jan 25 CT 4m
M8
1.879
···
···
L8?i
1.046
2002 Jan 27 CT 1.5m
M7.5
1.070
2002 Jan 24 KP 4m
M7
1.122
2002 Jan 23 CT 4m
M9
1.3543(24)-13331l/(15.7)]TJ/F238.96Tf40.10TD[(
±0.2
J − KS
Table 3.7 (cont’d)
d
(pc)
Other
Ref.
11.2±0.2 13.3±1.1 11,10
14.8±0.2 18.6±2.2
12,6
11.0±0.2 18.9±1.8
10.7±0.3 15.6±1.8
11.5±0.1 15.7±1.0
)]TJ/F118.96Tf7.160T9.34562458.90TD[(
18.9±0.211,10
)]T9]TJ/
MJ
94
G 216-7B
2104149−103736
2237325+392239
13.846
13.346
J
0.887
0.664
J −H
1.491
1.192
J − KS
2001 Jul 15
···
Obs.
Date
KP 4m
···
Telescope
L3
M9.5
Spectral
Type
12.7±0.2
11.6±0.1
MJ
17.2±1.6
22.3±1.4m
d
(pc)
15
Other
Ref.
References. — (1) Paper III; (2) Wilson (2002); (3) Liebert et al. (2003); (4) Kendall et al. (2003) (5) Schneider et al. (2002); (6)
Geballe et al. (2002); (7) Hawley et al. (2002); (8) McCaughrean, Scholz, & Lodieu (2002); (9) Phan-Bao et al. (2003); (10) Gizis
(2002); (11) Ruiz, Wischnjewsky, Rojo, & Gonzalez (2001); (12) Fan et al. (2000); (13) Paper IV; (14) Lépine, Rich, & Shara (2003);
(15) Kirkpatrick et al. (2001)
dπ = 18.9 ± 0.7 (ESA 1997)
Has Li I absorption and Hα emission. See § 3.6.2
m
l
dπ = 5.67 ± 0.02 (Paper IV)
ST from Wilson (2002)
k
ST from Fan et al. (2000)
j
Low galactic latitude and is either a late-L dwarf or a reddened background star.
h
i
Has strong Hα emission. See § 3.6.3
Has Li I absorption. See § 3.6.2
g
ST change from M6 in Paper III
f
Binary with MJ = 10.96 and 12.06 (L. Close, in preparation). d = 11.1 pc.
e
d
ST T0 in NIR Geballe et al. (2002)
ST change from M6 in Paper III
b
c
ST from Wilson (2002)
a
Note. — MJ and distances listed are estimates obtained using our calibration. Data for multiple systems are based on the system’s
combined spectral type and photometry and are marked with parentheses.
Other
Names
2MASSI
Designation
Table 3.7 (cont’d)
95
0021508+422050
0022137+120305
0025576+391136
0036448−203131
0049267−063546
0055294+511536
0107042+243527
0117474−340325
0120491−074103
0124598+284758
0141148−241731
0211508+472830
0214002+424336
0215159+434732
0218291−313322
0218578−061749
0219280−193841
0228110+253738
0228330+181109
0239424−173547
0241536−124106
0257545+411132
0314401−045031
0316451−284852
0320283−044635
0326422−210205
0355047−103241
0408290−145033
0423532−000658
0428509−225322
0430515−084900
2MASSI
Designation
LP 649- 93
[LE 36] 2
Other
Names
14.283
13.469
13.565
14.383
13.347
13.465
13.507
15.184
12.976
13.354
13.437
12.841
14.239
13.301
14.715
12.920
14.092
13.851
13.226
14.310
15.662
13.964
12.656
14.586
13.249
16.111
13.085
14.211
13.664
13.579
12.954
J
0.774
0.661
0.654
0.710
0.779
0.738
0.770
0.970
0.684
0.738
0.673
0.632
0.780
0.744
0.906
0.734
0.793
0.871
0.654
0.789
1.054
0.754
0.653
0.837
0.708
1.337
0.629
0.887
0.681
0.882
0.689
J −H
Table 3.8.
1.310
1.023
1.084
1.309
1.246
1.167
1.288
1.700
1.122
1.117
1.135
1.017
1.277
1.111
1.539
1.060
1.262
1.400
1.023
1.305
1.759
1.237
1.035
1.478
1.137
2.226
1.142
1.431
1.166
1.459
1.174
J − KS
2002
2001
2002
2002
2002
2001
2001
2002
2002
2001
2002
2001
2002
2000
2002
2000
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
···
2002
Jan 27
Jan 25
Jul 21
Jan 25
Jan 25
Jan 26
Jul 16
Jul 14
Jan 25
Jan 28
Jul 21
Jan 31
Jul 14
Jan 25
Oct 02
Jan 24
Oct 01
Jan 25
Jan 23
Jan 22
Jan 26
Jan 26
Jan 25
Jan 23
Jan 24
Jan 31
Jan 24
Jan 25
Jan 24
Jan 26
Obs.
Date
KP 4m
KP 4m
KP 4m
CT 4m
CT 4m
KP 4m
KP 4m
CT 4m
CT 1.5m
KP 4m
CT 1.5m
KP 4m
KP 4m
KP 2.1m
CT 4m
KP 2.1m
CT 4m
KP 4m
KP 4m
CT 4m
CT 4m
KP 4m
CT 4m
CT 4m
CT 1.5m
CT 4m
KP 4m
CT 4m
CT 4m
···
CT 1.5m
Telescope
M9?
M7.5
M8
M9?
M8.5
M7.5
M9
L2?
M8?
M8
M7.5
M7
M9?
M7
L3
M8a
L1
L0?
M7
L0
L2?
M9?
M7.5
L0?
M8?
L5?
M8.5
L2
M8.5
L0.5b
M8
Spectral
Type
M7–L8 Dwarfs Discovered Outside 20 pc
11.5±0.3
11.0±0.2
11.2±0.2
11.5±0.3
11.3±0.2
11.0±0.2
11.5±0.1
12.3±0.3
11.2±0.4
11.2±0.2
11.0±0.2
10.7±0.3
11.5±0.3
10.7±0.3
12.7±0.2
11.2±0.2
12.0±0.1
11.7±0.3
10.7±0.3
11.7±0.1
12.3±0.3
11.5±0.3
11.0±0.2
11.7±0.3
11.2±0.4
13.6±0.9
11.3±0.2
12.3±0.2
11.3±0.2
11.9±0.1
11.2±0.2
MJ
36.6±4.7
31.7±3.1
30.3±2.5
38.3±4.9
25.4±1.8
31.6±3.1
25.6±1.7
37.6±5.9
23.1±3.8
27.5±2.3
31.2±2.0
26.4±3.1
35.9±4.6
32.6±3.8
25.6±2.4
22.5±1.9
26.2±1.8
26.6±3.2
31.5±3.7
32.8±2.1
46.8±7.4
31.6±4.1
21.8±2.1
37.3±4.5
26.2±4.3
32.5±14.2
22.5±1.6
24.0±1.9
29.4±2.1
22.0±1.4
22.9±1.9
d
(pc)
6
1
1
4,2
5
1
3
2
1
Other
Ref.
96
0436276+115124
0436278−411446
0445111−060252
0445323−364225
0451009−340214
0453264−175154
0455326−270149
0508494−164716
0512063−294954
0528443−325222
0600337−331426
0608023−294459
0614528+453655
0644143−284141
0657254−401913
0657557+402942
0703269+463216
0704493+505155
0706285+385824
0710490+280909
0721462+193744
0730489+155312
0736017+204048
0740557+411409
0754054+160317
0819460+165853
0827202+450204
0829324−023854
0829490−001224
0839160+125354
0850017−192418
2MASSI
Designation
Other
Names
13.788
13.105
13.306
13.286
13.564
15.153
14.434
13.713
15.517
13.736
13.203
13.839
13.003
13.829
12.747
13.285
13.494
13.689
12.858
13.398
12.958
14.036
13.647
13.521
13.679
13.798
13.370
13.921
13.524
13.705
12.816
J
0.699
0.689
0.729
0.593
0.724
1.107
0.803
0.749
1.387
0.725
0.746
0.684
0.755
0.732
0.593
0.613
0.732
0.665
0.650
0.662
0.595
0.702
0.676
0.688
0.577
0.696
0.623
0.703
0.702
0.620
0.682
J −H
1.203
1.043
1.068
1.071
1.270
1.686
1.343
1.213
2.231
1.109
1.203
1.155
1.234
1.136
1.070
1.020
1.152
1.123
1.035
1.040
1.020
1.234
1.068
1.090
1.075
1.169
1.053
1.144
1.067
1.166
1.189
J − KS
2002
···
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
30
30
26
23
26
25
23
26
25
26
22
25
27
23
23
23
25
24
23
22
25
23
23
23
24
25
31
25
23
Jan 26
Obs.
Date
Table 3.8 (cont’d)
CT 4m
···
CT 1.5m
CT 1.5m
CT 4m
CT 4m
CT 4m
CT 4m
CT 4m
CT 4m
CT 4m
CT 4m
KP 4m
CT 4m
CT 1.5m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
CT 4m
CT 1.5m
KP 4m
CT 4m
Telescope
M9?
M7.5c
M7
M9?
L0.5
L3?
M9?
M8
L4?
M8.5
M7.5
M8.5
M9
M8
M7.5
M8
M8
M7.5
M7
M7?
M7.5
M9
M7
M8
M8
M9
M8
M8
M7?
M9
M8
Spectral
Type
11.5±0.3
11.0c
10.7±0.3
11.5±0.3
11.9±0.1
12.7±0.4
11.5±0.3
11.2±0.2
13.1±0.9
11.3±0.2
11.0±0.2
11.3±0.2
11.5±0.1
11.2±0.2
11.0±0.2
11.2±0.2
11.2±0.2
11.0±0.2
10.7±0.3
10.7±0.5
11.0±0.2
11.5±0.1
10.7±0.3
11.2±0.2
11.2±0.2
11.5±0.1
11.2±0.2
11.2±0.2
10.7±0.5
11.5±0.1
11.2±0.2
MJ
29.1±3.8
26.6c
32.7±3.8
23.1±3.0
21.9±1.4
31.3±5.7
39.2±5.1
32.5±2.7
30.5±12.5
30.4±2.2
28.0±2.7
31.9±2.3
20.3±1.3
24.3±2.8
22.7±2.2
26.7±2.2
29.4±2.4
35.1±3.4
26.6±3.1
34.1±7.9
25.1±2.4
32.7±2.2
38.3±4.5
29.7±2.5
32.0±2.7
29.3±1.9
27.7±2.3
35.7±3.0
36.1±8.4
28.1±1.9
21.5±1.8
d
(pc)
2
Other
Ref.
97
1011002+424503
1013279+352053
1017075+130839
1018431−162427
1019568+732408
1028307+740841
1054416+121408
1059513−211308
1117369+360936
1118387+233948
1123360+124122
1124552+231522
1130476−221033
1141440−223215
1152426+243807
1158027−254536
1158248+135445
1202256−062902
0856479+223518
0857278−033239
0902146−064209
0903351−063733
0912452+242549
0913044−073304
0916150+213951
0928256+423054
0934292−135243
0939145+395021
0940161+401736
1003191−010507
2MASSI
Designation
LHS 5165/
DENIS-P J1003−0105
TVLM 263-71765
Other
Names
13.357
14.271
14.111
13.771
12.884
12.911
12.483
14.536
14.220
14.045
14.030
13.715
13.836
12.651
13.033
13.528
13.944
13.695
15.647
14.378
13.763
13.702
13.520
13.403
13.218
13.090
13.053
13.724
13.583
12.352
J
0.657
0.723
0.879
0.643
0.637
0.644
0.670
0.784
0.734
0.751
0.778
0.670
0.726
0.657
0.766
0.678
0.747
0.691
1.068
0.804
0.694
0.668
0.654
0.790
0.718
0.708
0.614
0.689
0.685
0.667
J −H
1.056
1.261
1.435
1.117
1.100
1.009
1.020
1.366
1.240
1.246
1.243
1.123
1.115
1.090
1.286
1.052
1.208
1.109
1.723
1.349
1.092
1.071
1.062
1.272
1.147
1.119
1.017
1.194
1.146
1.085
J − KS
···
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
···
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Jan
Obs.
Date
Table 3.8 (cont’d)
23
23
24
22
25
25
23
24
24
25
25
24
23
24
26
25
26
22
23
26
26
25
23
24
24
30
24
23
···
KP 4m
KP 4m
CT 4m
KP 4m
KP 4m
KP 4m
CT 4m
KP 4m
KP 4m
KP 4m
KP 4m
CT 4m
CT 4m
KP 4m
CT 4m
KP 4m
CT 4m
KP 4m
CT 4m
CT 4m
CT 4m
KP 4m
CT 4m
KP 4m
KP 4m
CT 1.5m
KP 4m
KP 4m
···
Telescope
M7.5e
M9?
L2?
M7.5
M8.5
M7
M7.5
L1
L0?
M9
M7
M8
M8
M7.5
M9
M8
M9
M9
L3?
M9.5
M7
M7
M7
M9
M8?
M8.5
M7?
M8?
M7.5
M7d
Spectral
Type
11.0e
11.5±0.3
(12.3±0.3)
11.0±0.2
11.3±0.2
10.7±0.3
11.0±0.2
12.0±0.1
11.7±0.3
11.5±0.1
10.7±0.3
11.2±0.2
11.2±0.2
11.0±0.2
11.5±0.1
11.2±0.2
11.5±0.1
11.5±0.1
(12.7±0.4)
11.6±0.1
10.7±0.3
10.7±0.3
10.7±0.3
11.5±0.1
11.2±0.7
11.3±0.2
10.7±0.5
11.2±0.4
11.0±0.2
10.7±0.3
MJ
31.3±2.8e
36.4±4.7
(22.9±3.6)
36.4±3.6
20.6±1.5
27.3±3.2
20.1±2.0
32.1±2.2
31.5±3.8
32.8±2.2
45.6±5.4
32.5±2.7
34.4±2.9
21.8±2.1
20.6±1.4
29.8±2.5
31.3±2.1
27.9±1.9
(39.3±7.2)
35.9±2.3
40.3±4.7
39.2±4.6
36.1±4.2
24.4±1.6
25.9±8.4
22.6±1.6
29.1±6.8
32.6±5.3
33.4±3.3
21.1±2.5
d
(pc)
2
1,11
10
8,9
1
7
Other
Ref.
98
1202366−060405
1204303+321259
1217293+003532
1218595−055028
1220116+331538
1227154−063645
1247357−121951
1304075+403615
1305213+224502
1305410+204639
1330023−045320
1339265−175505
1413598−045748
1421187−161820
1430435+291540
1436097+290035
1438454+555913
1452184+482621
1456014−274735
1614155+821132
1626569+395448
1646115+501945
1707333+430130
1717140+652622
1743348+584411
1744571+374710
1801455+744229
1822471+392150
1852168+525719
2004536−141622
2014035−201621
2MASSI
Designation
SDSS J1717+6526
Other
Names
13.963
13.883
13.121
14.059
13.423
14.142
13.886
13.205
13.983
15.232
13.315
13.424
13.394
12.769
14.279
13.312
13.095
13.342
13.269
13.619
13.275
13.620
13.962
14.940
14.016
13.820
13.135
13.430
13.480
13.169
12.527
J
0.690
0.805
0.597
0.700
0.649
0.746
0.689
0.672
0.748
1.149
0.616
0.706
0.695
0.660
0.859
0.665
0.684
0.675
0.611
0.778
0.637
0.625
0.757
1.089
0.863
0.657
0.666
0.653
0.646
0.660
0.665
J −H
1.155
1.342
1.004
1.322
1.054
1.235
1.166
1.057
1.250
1.760
1.099
1.134
1.161
1.094
1.533
1.142
1.058
1.038
1.066
1.179
1.016
1.042
1.305
1.745
1.347
1.107
1.098
1.015
1.146
1.117
1.092
J − KS
2002
2002
2002
2002
2001
2002
2002
2001
2002
2002
2002
2002
2002
2002
2002
2002
2001
2001
2002
2001
2001
2001
2001
···
2001
2001
2001
2001
2001
2001
2001
Jul
Jul
Jul
Jul
Jul
Jul
Jul
19
19
16
16
15
16
15
Jan 23
Jan 23
Jan 24
Jan 23
Jul 20
Jan 24
Jan 24
Jul 16
Jan 25
Jan 24
Jan 25
Jan 25
Jan 25
Jan 31
Jan 25
Jan 24
Jul 21
Jul 21
Jan 26
Jul 21
Jul 21
Jul 19
Jul 19
Obs.
Date
Table 3.8 (cont’d)
CT 4m
KP 4m
KP 4m
CT 4m
KP 4m
CT 4m
CT 4m
KP 4m
KP 4m
KP 4m
CT 4m
CT 4m
CT 4m
CT 1.5m
KP 4m
KP 4m
KP 4m
KP 4m
CT 4m
KP 4m
KP 4m
KP 4m
KP 4m
···
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
KP 4m
Telescope
M8
L0
M7.5
M8.5
M7
M9
M8.5
M7
M8
L4?
M8
M7.5
M8
M7.5
L2
M8.5
M7
M7
M9
M8?
M7.5
M7
L0.5f
L4g
M9.5
M7
M7
M7.5
M8
M7.5
M7.5
Spectral
Type
11.2±0.2
11.7±0.1
11.0±0.2
11.3±0.2
10.7±0.3
11.5±0.1
11.3±0.2
10.7±0.3
11.2±0.2
13.1±0.4
11.2±0.2
11.0±0.2
11.2±0.2
11.0±0.2
(12.3±0.2)
11.3±0.2
10.7±0.3
10.7±0.3
11.5±0.1
11.2±0.4
11.0±0.2
10.7±0.3
11.9±0.1
13.1±0.2
11.6±0.1
10.7±0.3
10.7±0.3
11.0±0.2
11.2±0.2
11.0±0.2
11.0±0.2
MJ
36.4±3.0
26.9±1.7
27.0±2.6
35.3±2.6
34.5±4.0
34.3±2.3
32.6±2.4
31.2±3.6
36.8±3.0
26.8±5.5
27.0±2.2
31.1±3.0
28.0±2.3
23.0±2.2
(24.8±2.0)
25.0±1.8
29.7±3.5
33.2±3.9
22.9±1.5
31.1±5.1
29.0±2.8
37.8±4.4
26.3±1.7
23.4±2.4
30.4±1.9
41.4±4.8
30.2±3.5
31.1±3.0
29.2±2.4
27.6±2.7
20.5±2.0
d
(pc)
12
9
11
1
Other
Ref.
99
2019269−250244
2039131−112653
2047317−080820
2107316−030733
2214506−131959
2228304+344034
2238074+435317
2247017+195528
2252014−181558
2254519−284025
2259324+445028
2MASSI
Designation
Other
Names
13.698
13.808
13.670
14.222
13.458
13.538
13.839
13.829
13.570
14.161
13.340
J
0.714
0.656
0.704
0.772
0.744
0.633
0.809
0.738
0.730
0.717
0.598
J −H
1.249
1.150
1.078
1.306
1.133
1.025
1.320
1.224
1.158
1.264
1.006
J − KS
2001
2001
2001
2001
2001
2001
2001
2001
2001
2001
2001
Jul
Jul
Jul
Jul
Jul
Jul
Jul
Jul
Jul
Jul
Jul
Obs.
Date
18
18
18
18
15
18
18
19
19
18
15
Table 3.8 (cont’d)
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
Telescope
M8
M8
M7
L0
M7.5
M7
L1.5
M9
M8.5
L0.5
M7.5
Spectral
Type
11.2±0.2
11.2±0.2
10.7±0.3
11.7±0.1
11.0±0.2
10.7±0.3
12.1±0.2
11.5±0.1
11.3±0.2
11.9±0.1
11.0±0.2
MJ
32.3±2.7
33.9±2.8
38.7±4.5
31.5±2.0
31.5±3.1
36.4±4.2
21.8±1.6
29.7±2.0
28.2±2.0
28.8±1.9
29.9±2.9
d
(pc)
Other
Ref.
100
LP 763- 38
Other
Names
13.630
13.593
13.650
12.246
13.492
J
0.621
0.708
0.712
0.643
0.651
J −H
1.044
1.065
1.196
1.040
1.025
J − KS
2001
2001
2001
2001
2001
Jul
Jul
Jul
Jul
Jul
Obs.
Date
19
21
21
21
15
KP
KP
KP
KP
KP
4m
4m
4m
4m
4m
Telescope
M7.5
M7
M8.5
M7
M7h
Spectral
Type
11.0±0.2
10.7±0.3
11.3±0.2
10.7±0.3
10.7±0.3
MJ
34.1±3.4
37.3±4.4
29.2±2.1
20.1±2.4
35.6±4.2
d
(pc)
4
Other
Ref.
Displays strong Hα emission. See § 3.6.3
h
References. — (1) Wilson (2002); (2) Phan-Bao et al. (2003); (3) Luyten & Ebbighausen (1936); (4) Paper III; (5) Lodieu,
Scholz, & McCaughrean (2002); (6) Kendall et al. (2003); (7) Bouy et al. (2003); (8) Phan-Bao et al. (2001); (9) Gizis (2002);
(10) Tinney, Reid, Gizis, & Mould (1995); (11) Gizis et al. (2003); (12) Hawley et al. (2002)
ST from Hawley et al. (2002)
Displays strong Hα emission. See § 3.6.3
Data listed are based on photometric distance from Tinney, Reid, Gizis, & Mould (1995).
ST from Gizis (2002)
g
f
e
ST from Kendall et al. (2003)
ST change from M6 in Paper III
Data listed are based on photometric distance from Phan-Bao et al. (2003).
d
c
b
a
Note. — MJ and distances listed are estimates obtained using our calibration. Data for multiple systems are based on the
system’s combined spectral type and photometry and are marked with parentheses.
2326266+134552
2329129+270415
2336164+183500
2337149−083808
2351296+451926
2MASSI
Designation
Table 3.8 (cont’d)
101
0.706
0.602
0.591
0.643
0.625
0.649
0.641
0.724
0.633
0.633
J −H
1.121
1.033
1.045
1.014
1.019
1.054
1.021
1.054
1.001
1.006
J − KS
2002
2002
2000
2002
2002
2002
2001
2001
Jan 27
Jan 28
Sep 30
Jan 24
Jan 27
Jan 24
Jul 16
Jul 15
2000 Sep 30
2000 Sep 30
Obs.
Date
CT
CT
KP
KP
CT
KP
KP
KP
1.5m
1.5m
2.1m
4m
1.5m
4m
4m
4m
KP 2.1m
KP 2.1m
Telescope
M6
M6.5
M6b
M5.5
M6.5
M6.5
M6.5
M6c
M5
M6.5a
Spectral
Type
Early-type M Dwarfs Discovered Within 20 pc
References. — (1) Paper III; (2) Wilson (2002); (3) Phan-Bao et al. (2003)
ST change from M5.5 in Paper III
ST change from M5.5 in Paper III
b
c
ST change from M5.5 in Paper III
11.957
11.358
11.060
11.042
11.809
12.217
11.919
11.439
10.717
10.472
J
a
LP 698- 2
LP 714- 37
LP 645- 53
LHS 1363/
LP 649- 72
0035441−054110
0214125−035743
0334106−213034
0354200−143738
0410480−125142
1124532+132253
1424187−351432
1431304+171758
1847034+552243
2132297−051158
Other
Names
2MASSI
Designation
Table 3.9.
10.1±0.4
10.5±0.3
10.1±0.4
9.6±0.2
10.5±0.3
10.5±0.3
10.5±0.3
10.1±0.4
9.4±0.3
10.5±0.3
MJ
23.3±4.0
15.2±2.1
15.4±2.7
19.8±1.9
18.6±2.6
22.5±3.2
19.6±2.8
18.4±3.2
18.7±2.3
10.1±1.4
d
(pc)
1,3
1,2,3
1
1
Other
Ref.
102
0422205−360608
0439340−323551
0502386−322750
0701058+261412
0835432+313932
0904465+474634
0926332−015102
0951328+241737
1010426+194406
1021513−032309
1104335−051043
1129338−023311
1231546+513039
1233231+284158
1242283+265251
1252170+335739
1340115−145159
1344492−122848
1431156−131824
1445062+440939
0014083+493433
0017533+145324
0030198+314125
0104081+362301
0219331+141632
0234295+361311
0250023−080841
0301032+441656
0336489−241801
0413398−270429
2MASS
Designation
LP 740- 25
LP 267-299
LP 890- 2/
DENIS-P J0413−2704
LP 651- 17/LHS 1450
Other
Names
12.421
11.601
12.458
13.112
13.528
13.573
12.931
13.309
13.281
12.359
13.376
9.539
13.243
13.254
12.649
12.246
13.530
12.064
11.136
12.439
13.276
13.204
13.383
13.064
12.725
12.459
11.878
12.059
9.905
12.214
J
Table 3.10.
0.650
0.560
0.623
0.661
0.639
0.660
0.656
0.557
0.652
0.612
0.644
0.542
0.649
0.678
0.632
0.645
0.678
0.599
0.640
0.633
0.621
0.690
0.630
0.637
0.660
0.637
0.652
0.681
0.530
0.636
J −H
1.056
1.006
1.047
1.045
1.029
1.028
1.040
1.056
1.080
1.007
1.112
1.052
1.005
1.051
1.002
1.007
1.041
1.001
1.015
1.018
1.022
1.056
1.006
1.015
1.014
1.002
1.028
1.061
1.003
1.024
J − KS
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2001
2001
2001
2002
2002
2002
2001
2001
2001
2001
2001
2001
2000
2000
2000
2002
2000
Jan 27
Jan 27
Jan 26
Jan 24
Jan 24
Jan 25
Jan 26
Jan 24
Jan 24
Jan 27
Jan 24
Jan 27
Jan 24
Jul 20
Jul 16
Jul 16
Jan 26
Jan 31
Jan 27
Jul 21
Jul 15
Jul 16
Jul 21
Jul 23
Jul 23
Sep 30
Sep 30
Oct 02
Jan 27
Sep 30
Obs.
Date
CT
CT
CT
KP
KP
KP
CT
KP
KP
CT
CT
CT
KP
KP
KP
KP
CT
CT
CT
KP
KP
KP
KP
KP
KP
KP
KP
KP
CT
KP
1.5m
1.5m
4m
4m
4m
4m
4m
4m
4m
1.5m
4m
1.5m
4m
4m
4m
4m
4m
1.5m
1.5m
4m
4m
4m
4m
4m
4m
2.1m
2.1m
2.1m
1.5m
2.1m
Telescope
M6.5
M5.5
M6.5
M6.5
M6
M5
M6
M5
M6.5
M6.5
M6
M2
M6.5
M5.5
M5
M5.5
M6.5
M3
M5
M6.5
M6
M6.5
M4
M5
M4
M6a
M5.5
M6
M3
M6
Spectral
Type
Early-type M dwarfs Discovered Outside 20 pc
10.5±0.3
9.5±0.5
10.5±0.3
10.5±0.3
10.1±0.4
9.7±0.3
10.1±0.4
9.8±0.2
10.5±0.3
10.5±0.3
10.1±0.4
6.9±0.2
10.5±0.3
9.5±0.3
9.4±0.5
9.4±0.2
10.5±0.3
7.3±0.2
9.2±0.3
10.5±0.3
10.1±0.4
10.5±0.3
8.9±0.2
9.4±9.3
7.6±0.3
10.1±0.4
9.7±0.2
10.1±0.4
7.5±0.2
10.1±0.4
MJ
24.7±3.5
26.0±5.7
25.1±3.6
34.0±4.8
48.1±8.3
60.6±9.3
36.5±6.3
49.9±4.4
36.7±5.2
24.0±3.4
44.8±7.7
34.3±3.2
36.1±5.1
56.9±6.6
44.0±9.1
36.4±3.7
41.2±5.8
90.1±9.2
23.9±3.0
24.9±3.5
42.8±7.4
35.5±5.0
77.4±6.2
54.8±7.1
104±13
29.4±5.1
26.9±2.7
24.5±4.2
30.3±2.8
26.3±4.5
d
(pc)
4
2,3
2
2
1
Other
Ref.
103
12.956
13.170
12.489
13.325
12.758
12.811
12.647
12.494
13.331
13.204
11.275
12.713
13.509
12.528
11.331
13.153
12.559
13.220
13.117
12.012
13.099
12.304
11.461
J
0.688
0.679
0.660
0.604
0.663
0.612
0.687
0.636
0.613
0.629
0.632
0.661
0.654
0.646
0.572
0.684
0.654
0.610
0.657
0.626
0.654
0.642
0.610
J −H
1.048
1.066
1.066
1.041
1.020
1.006
1.071
1.040
1.018
1.024
1.004
1.021
1.012
1.024
1.099
1.051
1.010
1.007
1.007
1.014
1.008
1.029
1.034
J − KS
2001
2001
2001
2001
2001
2001
2001
2001
2001
2001
2001
2001
2001
2001
2000
2001
2001
2001
2001
2001
2001
2000
2001
Jul 21
Jul 21
Jul 14
Jul 21
Jul 19
Jul 15
Jul 15
Jul 15
Jul 16
Jul 16
Jul 18
Jul 15
Jul 18
Jul 16
Oct 01
Jul 15
Jul 14
Jul 15
Jul 15
Jul 15
Jul 15
Sep 29
Jul 21
Obs.
Date
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
2.1m
4m
4m
4m
4m
4m
4m
2.1m
4m
Telescope
M5
M6
M6.5
M5
M5
M6.5
M6.5
M3
M6.5
M5.5
M3
M5.5
M6.5
M6
M4
M6.5
M6.5
M6.5
M5.5
M5
M5
M6.5b
M6c
Spectral
Type
MJ
9.5±0.7
10.1±0.4
10.5±0.3
9.1±0.2
9.5±0.2
10.5±0.3
10.5±0.3
7.4±0.2
10.5±0.3
9.5±0.2
7.3±0.2
9.8±0.5
10.5±0.3
10.1±0.4
8.9±0.2
10.5±0.3
10.5±0.3
10.5±0.3
9.7±0.2
9.2±0.3
9.3±0.2
10.5±0.3
10.1±0.4
References. — (1) Wilson (2002); (2) Paper III; (3) Phan-Bao et al. (2001); (4) Phan-Bao et al. (2003)
ST change from M5.5 in Paper III
ST change from M5.5 in Paper III
b
c
ST change from M5 in Paper III
LP 763- 3/WT 2339
LP 695-351
Other
Names
a
1511512+303306
1516221+531631
1527192+413044
1543554+531521
1623388+161554
1626353+251235
1626373+604043
1732036+155715
1732281+300454
1809281+393608
1810005+405600
2015194−160133
2033573−042941
2041410−033353
2115408+165716
2125458−001834
2226368−023950
2240386−025056
2246444+294135
2246527+225517
2252051+255118
2317207−023632
2337383−125027
2MASS
Designation
Table 3.10 (cont’d)
49.8±16.5
40.8±7.0
25.5±3.6
71.6±8.0
44.4±4.7
29.6±4.2
27.4±3.9
104±10
37.6±5.3
55.1±5.6
63.2±6.8
38.8±8.4
40.8±5.8
30.3±5.2
30.8±2.3
34.6±4.9
26.3±3.7
35.7±5.1
48.2±5.4
36.3±4.6
57.8±6.2
23.4±3.3
18.6±3.2
d
(pc)
2
2,4
Other
Ref.
104
J
13.623
11.868
13.600
15.101
12.569
2MASSI
Designation
0253597+320637
0435145−141446
0608528−275358
0619526−290359
2234416+404138
0.693
1.236
0.702
0.882
0.735
J −H
1.079
1.927
1.210
1.649
1.138
J − KS
2002
2002
2002
2002
2000
Jan 25
Jan 24
Jan 25
Jan 24
Oct 02
Obs.
date
KP
CT
CT
CT
KP
4m
4m
4m
4m
2.1m
Telescope
Table 3.11. Young Objects
strong Hα emission
enhanced VO absorption
Comments
J
10.393
10.177
9.998
13.213
12.505
12.337
12.098
10.161
9.144
9.976
9.082
13.271
15.834
9.835
9.579
9.795
2MASSI
Designation
0012342−225516
0028097+121719
0036441−060858
0229220−110612
0252543−114220
0424503−740443
0436168−641131
0534324−121631
0613001−163648
0614035−230347
0636411−324041
0647027−622725
0827311−110002
0846564−204807
1010187−043536
1035438−091625
0.779
0.883
0.785
0.687
0.813
0.760
0.863
0.721
0.758
0.832
0.737
0.510
1.210
0.858
0.764
0.697
J −H
1.125
1.392
1.139
1.325
1.171
1.162
1.275
1.078
1.091
1.249
1.052
1.067
1.930
1.313
1.087
1.107
2002
2000
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
Jan 31
Oct 02
Jan 28
Jan 31
Jan 30
Jan 26
Jan 26
Jan 27
Jan 27
Jan 27
Jan 27
Jan 31
Jan 25
Jan 27
Jan 27
Jan 27
Obs.
date
CT
KP
CT
CT
CT
CT
CT
CT
CT
CT
CT
CT
CT
CT
CT
CT
1.5m
2.1m
1.5m
1.5m
1.5m
4m
4m
1.5m
1.5m
1.5m
1.5m
1.5m
4m
1.5m
1.5m
1.5m
Telescope
M1
M5
M1
M0
M1
M8
M5
M0
M1
M4
M0
M3
M0
M6
M1
M3
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III pec
Spectral
Type
Spectroscopically Confirmed Giants
J − KS
Table 3.12.
variable Hα
Comments
106
J
11.117
11.451
10.120
11.532
13.471
11.502
2MASSI
Designation
2025585−274618
2231451−233245
2244246+133701
2332026+243843
2336511+482441
2346447+160359
1.253
0.766
1.169
0.819
0.907
0.917
J −H
2.033
1.200
1.829
1.193
1.339
1.346
J − KS
2001
2001
2000
2000
2001
2000
Jul 15
Jul 16
Oct 02
Oct 02
Jul 14
Oct 02
Obs.
date
Table 3.12 (cont’d)
KP
KP
KP
KP
KP
KP
4m
4m
2.1m
2.1m
4m
2.1m
Telescope
M6
M3
M4
M3
M5
M7
III
III pec
III
III
III
III
Spectral
Type
Hα in emission
Comments
107
13.673
13.490
13.227
13.185
12.638
9.829
12.826
13.060
12.816
9.250
9.532
13.571
12.594
13.307
10.934
11.056
0236246−204103
0402332−681623
0426387+142516
0431342−723208
0459495−750918
0614383−135137
0635542−645226
0654386−713059
0701081−681854
0837170−132114
0843554−122407
1501069−053138
1515110−133227
1622328+423753
2206536−250628
2217099−260703
0.768
1.420
1.211
1.234
1.327
0.789
0.945
1.244
1.307
1.046
0.991
1.223
1.078
0.776
1.178
1.233
J −H
1.224
2.372
2.014
1.958
2.325
1.127
1.395
2.083
2.273
1.548
1.511
2.065
1.809
1.385
2.012
2.174
J − KS
2002
2002
2000
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2001
2001
2001
Jan 26
Jan 31
Oct 02
Jan 31
Jan 26
Jan 27
Jan 23
Jan 30
Jan 30
Jan 27
Jan 27
Jan 31
Jan 31
Jul 15
Jul 14
Jul 14
Obs.
Date
CT
CT
KP
CT
CT
CT
CT
CT
CT
CT
CT
CT
CT
KP
KP
KP
4m
1.5m
2.1m
1.5m
4m
1.5m
4m
1.5m
1.5m
1.5m
1.5m
1.5m
1.5m
4m
4m
4m
Telescope
yes (12/79–11/98)
no (12/92–01/00)
no (12/55–11/98)
no (01/93–12/98)
no (01/75–12/98)
no (11/83–01/99)
no (11/82–02/00)
no (02/91–12/98)
no (02/78–12/98)
no (01/82–02/99)
no (01/84–03/98)
no (07/84–02/99)
no (04/82–03/98)
yes (05/53–06/98)
no (07/77–11/98)
no (06/80–07/98)
Visual pma
(epochs)
Spectroscopically Confirmed Carbon Stars
Gizis (2002)
dC, LP 225-12b
dC, LP 830-18b
Comments
b
A discussion of these new carbon dwarfs will appear in P.J. Lowrance et al., in preparation.
Possible visual proper motion determined by PJL from examining DSS, XDSS and 2MASS images. Epochs listed
are either DSS–2MASS or XDSS R–2MASS.
a
J
2MASSI
Designation
Table 3.13.
Table 3.14.
MJ /Spectral Type Calibration Data
Name
Spectral
Typea
Gl 551
GJ 1286
GJ 1002
LHS 3339
Gl 412B
LHS 1443
LHS 1516
Gl 406
GJ 1111
LHS 191
LHS 2471
LHS 523
LHS 292
LHS 2930
LHS 429
LHS 3003
GRH 2208-20
TVLM 832-10443
LP 412-31
LHS 2397a
BRI 0246-1703
GL 569Ba
CTI 012657.5+280202
TVLM 513-46546
BRI 1222-1222
TVLM 868-110639
LHS 2065
LHS 2924
GL 569Bb
BRI 0021−0214
2MASSW J0149090+295613
PC 0025+0447
2MASSP J0345432+254023
HD 89744B
2MASSW J0746425+200032A
2MASSW J1439284+192915
2MASSW J1658038+702702
GJ 1048B
Kelu 1
GL 618.1B
2MASSW J1146345+223053A
DENIS-P 1058.7−1548
5.5
5.5
5.5
5.5
6
6
6
6
6.5
6.5
6.5
6.5
6.5
6.5
7
7
7.5
8
8
8
8
8.5
8.5
8.5
9
9
9
9
9
9.5
9.5
9.5
10
10
10.5
11
11
11
12
12.5
13
13
108
MJ
Ref.
9.68±0.01
9.90±0.05
9.98±0.03
10.05±0.06
10.04±0.01
10.09±0.20
10.11±0.26
10.15±0.01
10.40±0.02
10.43±0.08
10.47±0.09
10.60±0.11
10.62±0.03
10.77±0.04
10.72±0.03
10.91±0.06
10.88±0.07
10.83±0.04
10.98±0.05
11.13±0.08
11.42±0.19
11.18±0.08
11.44±0.06
11.72±0.06
11.34±0.14
11.49±0.17
11.55±0.04
11.66±0.04
11.69±0.08
11.44±0.11
11.63±0.05
11.78±0.25
11.77±0.06
11.93±0.07
11.81±0.05
11.87±0.04
11.97±0.04
12.03±0.13
12.03±0.09
12.90±0.18
12.58±0.08
12.95±0.06
1
1
1
3
1
2
2
1
1
3
3
2
1
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Table 3.14 (cont’d)
Name
2MASSW J0036159+182110
2MASSW J0326137+295015
GD 165B
2MASSW J1112257+354813
2MASSW J2224438−015852
LHS 102B
2MASSW J1328550+211449
2MASSW J1507476−162738
DENIS-P 1228.2−1547
DENIS-P 0205.4−1159
2MASSI J0825196+211552
GL 337C
2MASSW J1523226+301456
2MASSW J1632291+190441
a
Spectral
Typea
13.5
13.5
14
14.5
14.5
15
15
15
15
17
17.5
18
18
18
MJ
Ref.
12.71±0.04
12.90±0.12
13.23±0.17
12.88±0.06
13.77±0.04
13.20±0.24
13.38±0.27
13.49±0.04
13.56±0.10
13.85±0.08
14.97±0.04
14.14±0.09
14.79±0.08
14.89±0.09
3
3
3
3
3
3
3
3
3
3
3
3
3
3
M5 = 5, L0 = 10, L8 = 18
References. — (1) 8 pc Sample; (2) PMSU; (3) Dahn et al.
(2002)
109
Chapter 4
Meeting the Cool Neighbors. IX.
The Luminosity Function of
M7–L8 Type Ultracool Dwarfs
The first results of our search for ultracool dwarfs were described in the previous chapter and
here we present the remaining observations obtained in the far-red. We use these data to obtain a
robust estimate of the luminosity function.
This chapter is a manuscript in preparation for submission to The Astronomical Journal and
represents work done in collaboration with Neill Reid, James Liebert, Suzanne Hawley, Kevin Covey,
Peter Allen, and Finlay Mungall—their contributions are noted explicitly in the text. As with the
previous chapter, I am the primary author of the text and was responsible for obtaining and analyzing
the follow-up observations. I am also the sole keeper of the extensive database of targets. In addition,
I am the architect of the luminosity function analysis described in this chapter.
110
4.1
Introduction
In this paper we present the remainder of the follow-up far-red optical spectroscopy of the
2MU2 sample, nearby ultracool dwarfs culled from the 2MASS Second Incremental Release. In
§ 4.2 we briefly overview the creation of the sample and the reclassification of five objects from
Paper V. The observations are described in § 4.3 and spectral types, absolute magnitudes, and
distance estimates are presented in § 4.4. These data include many newly discovered late-type
dwarfs, including eight additions to the core sample of eighty-nine M7–L8 dwarfs within 20 pc used to
estimate the luminosity function. Finally, in § 4.5 we present the luminosity function and discuss the
statistical analysis used to obtain an estimate that is valid for spectral types M7–L8, corresponding
to 10.5 < MJ < 15. We discuss these results § 4.6 and briefly summarize our conclusions in § 4.7.
4.2
The 2MU2 Sample
The creation of the 2MU2 sample is discussed in detail in Paper V, however, we briefly summarize the procedures here. Eleven million point sources were selected from the 2MASS Second
Incremental Release with |b| > 10◦ and J − KS > 1. We narrowed the sample to 1672 objects
with optical and near-infrared color-color and color-magnitude criteria, positional coincidence with
star formation regions (e.g., Orion, Lupus), dense regions (e.g., LMC, M31), and other reddening
regions. The resulting sky coverage is 40%. The 588 objects with J ≤ 9 were analyzed separately
and, based on existing data, no late-type dwarfs were identified amongst them. The remaining 1084
fainter candidates were examined in detail. Visual inspection and cross-referencing with the Guide
Star Catalog and SIMBAD eliminated 447 objects, leaving 637 ultracool candidates. Of these, 112
were able to be classified with existing data. The remaining 525 require follow-up observations.
The sample described in Paper V, and summarized above, has been revised slightly. One object
that was originally rejected based on (F − J) color has been added back into the sample based on
observations presented by Thorstensen & Kirkpatrick (2003). Seven additional objects have been
rejected based on visual inspection. This results in 631 ultracool candidates, 112 were previously
known, thus 519 require follow-up observations.
The follow-up status of these 519 are shown in Figure 4.1. In Paper V, we presented our own
spectra of 298 objects and data for nine objects from other sources. Here we present spectra for a
further 174 objects, including new data for four of the nine objects with data from other sources.
We will present near-infrared data for twenty-seven objects too faint for optical follow-up with 4-m
class telescopes in a future paper. Only fifteen objects remain with no data—seven are at very
southern declinations (δ < −60◦ ) and clumped near either the LMC or SMC while the other eight
have J > 15.9 and will be targeted for future observations in the near-infrared and in the optical
with 8-m class telescopes.
111
4.3
Observations
Far-red spectroscopy was obtained for 174 objects with NOAO facilities and with University
of Washington access to the Apache Point Observatory (APO)1 . Tables 4.1–4.6 list the coordinates
(as a 2MASS name) and the near-infrared photometry from the 2MASS Second Release; the date
observed; telescope; and derived absolute magnitudes, distance estimates, and spectral types for all
of the observed objects2 . The instrumental setups and data reduction are the same as those used
for the data presented in Paper V.
Observations were obtained with the RC Spectrograph on the Kitt Peak 2.1-m telescope during
three separate runs: 2001 November 1–6 (Cruz and Reid), 2002 July 3–8 (Cruz and Allen), and
2003 March 13–15 (Cruz and Allen). For all three runs, the 400 line mm−1 grating, blazed at
8000 Å, was used with the OG 550 order blocking filter, to give spectra covering 6000–10000 Å.
Observations were made using a 1.00 2–1.00 5 slit to accommodate various conditions. Except for the
one object observed during 2001 November, internal quartz flats and HeNeAr arcs were used at each
position to correct for fringing.
Hawley and Covey used the Double Imaging Spectrograph (DIS II) on the 3.5-m telescope at
Apache Point Observatory on 2002 April 10, May 14 and 30, and July 10–11. The medium resolution
grating with 300 line mm−1 was used on the red camera to cover 6000–10000 Å at a resolution of
7.3 Å. Conditions were mostly clear with 0.00 8–1.00 2 seeing.
The MARS instrument on the Mayall 4-m telescope was used for three runs: 25–28 September
2002 (Cruz, Reid, and Liebert), 9–14 July 2003 (Cruz, Reid, and Mungall), and 10–12 February
2004 (Cruz and Reid). The VG0850-450 grism was used for all three runs with the slitwidths from
1.00 5–200 , to cover 6300–10000 Å at a spectral resolution 6–7 Å. An older CCD detector was used in
2002 September than in the two subsequent runs. The main difference between the two detectors
is the particle event rate which does not affect the data analysis presented here. In addition, the
conditions in 2003 July were significantly hampered by a combination of a nearly full moon and
smoke from the nearby Aspen Fire.
Cruz and Reid observed with the Blanco 4-m telescope on Cerro Tololo on 2003 April 20–23. A
Loral 3K CCD and the RC spectrograph with a 315 line mm−1 grating blazed at 7500 Å was used.
A 100 slit was implemented to cover the range 5500–10000 Å with a resolution of 5.5 Å (2.8 pixels)
and an OG 515 filter was used to block higher orders. All four nights were clear with seeing ranging
from 0.00 5 to 1.00 5.
Cruz obtained data with the CTIO 1.5 m on 2003 November 7–11 with a Loral 1K CCD and RC
Spectrograph. We were able to take advantage of a lunar eclipse on 9 November to observe several
fainter objects. We employed 1.00 5 slit, an OG 530 filter to block higher orders, and a 400 line mm−1
1 Spectra
are available upon request from K. L. C, [email protected].
2MASS designation is 2MASSI Jhhmmss[.]s±ddmmss. We note that the astrometry and photometry presented here is likely to be different from those listed in the 2MASS All-Sky Release.
2 The
112
grating blazed at 8000 Å to cover 6300–9000 Å at a resolution of 6.5 Å (3 pixels). Conditions were
clear and the seeing ranged from 0.00 7–0.00 9.
All of the data were bias-subtracted, flat-fielded (except 2001 November), wavelength-calibrated,
and flux-calibrated using the standard IRAF CCDRED package and the DOSLIT routine. HeNeAr
lamps were taken nightly to wavelength calibrate. Flux-calibration was done using observations of
the flux standards BD +26 2606, BD +17 4708, Feige 56, Feige 110, HD 19445, and Hiltner 600
(Oke & Gunn 1983; Hamuy et al. 1994).
4.4
Results
Spectral types enable absolute magnitudes and spectrophotometric distance estimates for ultracool dwarfs. These data are listed in Tables 4.1–4.3 for all of the dwarf targets. We list eight objects
with types M6 and later that appear to be within 20 pc; eighty-three more distant late-type objects;
and thirty-one distant, early-to-mid M dwarfs. Four objects with spectral features indicative of
low-mass dwarfs are listed Table 4.4.
The methods used to derive spectral types and absolute magnitudes are the same as described
in detail in Paper V. Spectral types are determined via side-by-side comparison with standard star
spectra. The uncertainty on spectral type is ±0.5 subtypes except where low signal-to-noise data
result in uncertainties of 1 or 2 types—these are noted by a question mark. MJ is estimated by using
the spectral type/MJ calibration derived in Paper V and is combined with 2MASS Second Release
J-band photometry to yield a distance. The uncertainties in both the derived MJ and distance are
dominated by the uncertainty in the spectral type.
Spectroscopy revealed several of the candidates to be distant giants and carbon stars. Rough
spectral types (±1) for the thirty-three giants are listed in Tables 4.5 and the fifteen carbon stars
are listed in Table 4.6.
4.5
The Luminosity Function
We identify 89 objects in 86 systems in 40% the sky (2MASS Second Release and |b| > 10)
with spectral types between M7 and L8 that appear to be within 20 pc of the Sun—we use these to
make the first estimate of the ultracool dwarf luminosity function (LF). These objects are listed in
Table 4.7 and their color-magnitude and color-color diagrams are shown in Figure 4.2.
The measured luminosity function is essentially complete to J = 14.5 (see Figure 4.1). There
are three objects with no observations that have J < 14.5, but these are likely to be one distant
(d > 50 pc) M dwarf and two carbon stars—all three are near the SMC. This completeness limit
corresponds to MJ = 13 (∼L3.5) at 20 pc. In addition, we are likely missing M7 dwarfs since several
are known with (J − KS ) < 1, VB 8 is an example. Thus our measured luminosity function is
113
formally complete from spectral types M8 to L3.5. However, as described in detail below, we are
able to use statistical methods to get a robust estimate of the luminosity function for types M7 to
L8.
4.5.1
Malmquist Bias
We have adopted a unique value of MJ for each spectral type, Mobs , where the true situation
is a dispersion of absolute magnitudes about some mean for each spectral type. As a result, the
sample is biased towards more luminous objects. The intrinsically less luminous objects (where
the true absolute magnitude, M0 , is greater than Mobs ) are systematically excluded because using
Mobs overestimates their distance and thus they are more likely to fall outside of the distance
limit. Similarly, a greater number of over-luminous objects are included in the sample because their
distances are underestimated. This is classical Malmquist Bias and we must correct the estimated
absolute magnitude for those objects in the sample without trigonometric parallax data (Malmquist
1920).
Since we expect nearby M and L dwarfs to be uniformly distributed throughout the Solar
Neighborhood we can use Malmquist’s formula to correct the absolute magnitudes,
M0 = Mobs − 1.38σ 2
where σ is the uncertainty in Mobs .
(4.1)
The uncertainty in Mobs depends on the scatter in the
MJ /spectral-type relation but is primarily due to the uncertainty in the assigned spectral type
and ranges from 0.2 to 0.4 mags resulting in corrections of 0.06 to 0.22 mags. The Malmquist
corrected MJ luminosity function, Φ(MJ ), is shown in Figure 4.3.
4.5.2
Incompleteness
We identify three sources of incompleteness in our 20 pc sample: 1) Observational incompleteness affects several absolute magnitude bins because we have not yet obtained follow-up observations
of 100% of the 2MU2 sample. We correct for this in the J bins where more than 50% of the objects
have been observed (14.5 < J < 15.5). 2) Observations are especially lacking at the faintest magnitudes (J > 15.5) severely affecting the completeness in the faintest two MJ bins. We interpret
this as a volume incompleteness rather than observational. 3) We are not complete at all spectral
types (specifically, M7, L7, and L8) because of the color-magnitude and color-color criteria that were
imposed. Each of these are discussed in the following subsections and corrections are derived where
appropriate.
4.5.2.1
Observational Incompleteness
Save three objects, all 2MU2 candidates lacking spectroscopic follow-up observations are fainter
than J = 14.5 (see Figure 4.1). Table 4.8 list the observational incompleteness (Nobs /Ntot ) as a
114
function of apparent magnitude, in half-magnitude bins. The incompleteness for J > 15.5 is very
significant (< 50% observed) and is more appropriately interpreted as a volume incompleteness and
is addressed in the following section. In this section we describe how we account for the observational
incompleteness for 14.5 < J < 15.5.
For the luminosity function, we are only considering late-M and L dwarfs (which occupy a finite
range of MJ ) that lie within 20 pc. Thus, each J bin corresponds to a discrete distance range
in each MJ bin of the luminosity function. We apply the completeness correction to the actual
number of objects in the 2MU2 sample that fall into the distance range affected in each MJ bin.
The corrections are summarized in Table 4.9 and the corrected luminosity function is shown as a
dotted line in Figure 4.3.
As an example of our method, consider the MJ =13.5–14 bin (second row of Table 4.9). We use
the mid-point of this bin, MJ = 13.75, to estimate the distance range affected. This bin is complete
to 14.1 pc since objects with MJ = 13.75 at distances nearer than 14.1 pc are brighter than our
observational completeness limit of J = 14.5—three objects fall into this distance range. Objects
with MJ = 13.75 and 14.5 < J ≤ 15.0, lie between 14.1 and 17.8 pc. Thus the 72.7% completeness
only applies to objects in this distance range. In our sample, we have uncovered three objects with
13.5 < MJ ≤ 14 that lie between 14.1 and 17.8 pc. Since these three objects represent 72.7% of
the observations, the corrected number is 3/72.7%=4.125 objects. Similarly, for 15.0 < J ≤ 15.5,
there are four objects that fall into the affected distance range (17.8 < d ≤ 20 pc), and the corrected
value is 4/63.6%=6.286 objects. The incompleteness at fainter J magnitudes is not relevant since,
for MJ = 13.75, those objects would lie at a distance greater than 20 pc. Taking the sum yields
the corrected number of objects in the 13.5 < MJ ≤ 14 bin, 3 + 4.125 + 6.286 = 13.411 (as opposed
to the uncorrected value of 10). The other affected MJ bins are corrected in a similar manner as
summarized in Table 4.9.
4.5.2.2
Volume Incompleteness
In Figure 4.4 we plot the run of density of the 2MU2 sample with increasing distance from the
Sun for five magnitude bins. (Note that these bins are coarser than that of the actual luminosity
function.) The distance at which the sample begins to be incomplete is indicated by a downturn in
the measured space densities. The sample appears to be complete to 20 pc in all but the faintest
magnitude bin. The 13.5 < MJ ≤ 14.5 bin, while appearing to be complete to 24 pc, only contains
two objects with 14 < MJ ≤ 14.5, reflecting the significant observational incompleteness at faint
magnitudes. We treat this and the subsequent bin as complete to the distance corresponding to
J = 14.5 and MJ = 14.25 and 14.75 respectively, and correct them by extrapolating the observed
density to the larger volume. The corrections to these two bins are detailed below.
We consider the 14 < MJ < 14.5 bin first. There are only two objects, both within the formal
completeness limit of 11.2 pc for this MJ bin (J = 14.5 with MJ = 14.25). (Since all of the objects
115
are within the observational completeness limit, we cannot correct this MJ bin in the manner as
described above.) Thus our measured space density is 2/(volume enclosed by 11.2 pc).We find the
corrected value using simple extrapolation:
corrected number =
2
× 203 = 11.3 objects.
11.223
There are also only two objects in the faintest bin (14.5 < MJ < 15). There is one object
within the formal completeness limit (d < 8.9 pc, J = 14.5 with MJ = 14.75) and one object in the
first distance range affected by observational incompleteness as described above (8.9 < d < 11.2 pc,
14.5 < J < 15). Correcting for the observed incompleteness (1/72.7%) yields 1.375 objects. Thus,
we estimate 2.375 objects within 11.2 pc and extrapolate that value to 20 pc.
corrected number =
2.375
× 203 = 13.45 objects.
11.23
We adopt these corrected space densities as our best estimate for these two bins and show them in
Figure 4.3 as a dashed histogram.
4.5.2.3
Spectral Type Incompleteness
We have estimated our incompleteness for spectral types M7–L8 out to 20 pc by using the data
available for ultracool dwarfs with parallax measurements and with J < 16.5. Shifting their MJ
magnitudes to a distance of 20 pc makes all of these objects appear as they would at the far edge of
our volume limit. We show these data in Figure 4.5 and mark the objects excluded by our selection
criteria. In addition, the M7s, M8s, and M9s in the 20 pc 2MU2 sample are delineated in Figure 4.2.
We discuss below blue M7s, unusual M9s and L0s, and L8s that are likely excluded from our sample.
The corrected space densities are shown as dot-dashed line in Figure 4.3.
Two blue M7 dwarfs, GRH 2208−2007 (M7.5) and VB 8 (M7), are excluded by both the
J/(J − KS ) and (J − H)/(H − KS ) selection criteria. We propose that these two objects simply lie
on the blue side of the intrinsic color distribution of M7s. As shown in Figure 4.2, the M8 sequence
is completely contained redward of (J − KS ) = 1, while the M7 sequence is clearly truncated by
this criterion. Therefore, we conclude that the 2MU2 sample is not complete for M7s and we need
to estimate the magnitude of the incompleteness.
GRH 2208 and VB 8 are two of the three M7s with parallax measurements and thus these
data are not adequate to estimate the fraction of M7s excluded by our selection criteria. Instead,
we look to previously known M7s and our proper-motion selected sample of nearby dwarfs selected
with (r − KS ) color. Based on this sample, where four of the thirteen M7s have (J − K) < 1, we
estimate 69±12% of M7s are redder than (J − K) = 1. Since twenty-two are present in the 20 pc
2MU2 sample, the corrected value is 31.8 (22/69%). This correction affects the brightest magnitude
bin of the luminosity function and is shown as a dot-dashed line in Figure 4.3.
The five faint, red objects that are excluded in J/(J − KS ) are four L8-type dwarfs and one
L7.5-type dwarf. There are a total of five L8s and four L7s total plotted. Based on this sample, we
116
are missing 80% of L8 dwarfs and 25% of the L7s. This is not surprising since it has been recently
shown that methane begins to appear in late-L dwarfs thus making their near-infrared colors bluer.
We show this correction in the two faintest bins as the dot-dashed line in Figure 4.3. However, this
effect is probably more accurately accounted for by the volume correction described above.
Three M9s and L0s are unusually blue in (H − K): PC 0025+0447 (M9.5), SDSS 1435−0046
(L0), and SDSS 2255−0034 (L0:). PC 0025 is recognized as an highly usual object with persistent,
extremely strong Hα emission (EW∼ 100 Å) yet no other features characteristic of a stellar flare such
as Ca, Na, or K in emission are present. The two SDSS objects are very faint and the photometric
errors on the colors are substantial. We propose that either these three objects are unusual in the
similar, as-yet-unrecognized way, or more likely, that the uncertainties in the 2MASS photometry,
either due to a systematic or coincidence, have resulted in a similar blue (H − K) color. We do not
apply any correction to the luminosity function based on these objects.
Two additional objects are excluded by the (J−H)/(H−K) selection criteria: 2MASS 0235−2331
(L1) and SDSS 1446+0024 (L5). The (J − H) color of 2M 0235 is unusually blue for its spectral
type and is probably due to the 0.1 uncertainties in both the J and H magnitudes. For an L5,
SDSS 1446 is unusually red in (J − H) and blue in (H − K) and the photometry is fairly robust with
uncertainties ranging from 0.035 in H band to 0.082 magnitudes in J band. Because the spectral
type is based on near-infrared data, the presence of methane, which might affect the colors, is not
likely. More data is needed to explain the anomalous colors of SDSS 1446. We do not apply any
corrections to the luminosity function based on these two objects.
4.5.3
Unresolved Binary Systems
A significant source of bias and incompleteness in our sample is unresolved binary systems.
Currently, there are only three binary systems included in the 20 pc sample (and the luminosity
function), a binary fraction of only 4%—significantly below the 15% estimate found by recent efforts
(Gizis et al. 2003; Bouy et al. 2003). Clearly, there are many unresolved systems in the 2MU2
sample. This will affect the luminosity function in two main ways: 1) as an overall incompleteness at
all absolute magnitudes because we are not including the contribution of the unresolved secondaries
to the space density and 2) as a bias that overestimates the space density of brighter objects since
the MJ of unresolved systems will be underestimated. While we do not currently correct for these
effects, we are involved in several efforts to uncover the binaries in the sample with ground-based
adaptive optics and space-based observations.
117
4.6
4.6.1
Discussion
The Luminosity Function
Our best estimate of the luminosity function (LF) of ultracool dwarfs is shown in the right
panel of Figure 4.3. There are three main points of discussion: 1) the effect of T dwarfs of the LF,
2) the change to an increasing LF at fainter magnitudes, and 3) how the combined 8 pc sample and
ultracool dwarf LF reflect the properties of low-mass stars and brown dwarf evolution. Each of these
points is addressed below.
Our estimate of the space densities of late-L dwarfs (L6–L8, 14 < MJ < 15) is a lower limit on
the full ultracool dwarf luminosity function, which includes M, L, and T dwarfs. Recent trigonometric
parallax results show that brown dwarfs brighten at MJ by as much as one magnitude even though
they are actually cooling in temperature as they evolve from L to T dwarfs (Dahn et al. 2002; Tinney,
Burgasser, & Kirkpatrick 2003). This brightening is probably a result of the clearing of clouds and a
lowering of the photosphere. As a result, the space densities of both late-L and early-to-mid T dwarfs
(T0–T5) contribute to the luminosity function in our faintest two magnitude bins (14 < MJ < 15).
Predicted space densities of brown dwarfs based on evolutionary models suggest that there might
be as many as ∼80 T0–T5 dwarfs within 20 pc (Burgasser 2004). Since we have only measured the
contribution from L dwarfs, our estimates of the space densities of objects with 14 < MJ < 15 are
a lower limit on the full ultracool dwarf LF.
As was first pointed out in Cruz et al. (2003), our measured luminosity function continues to
decrease towards fainter magnitudes until MJ = 13.75, where it turns around and the space density
of ultracool dwarfs begins to increase. Put simply, this implies that the field space density of late-L
dwarfs is greater than that of earlier type L dwarfs. As a test of the robustness of our measurement
of this turnaround, we consider the possibility that the true luminosity function remains constant
from 13.25 < MJ < 14.75. In this scenario, taking into account our estimated completeness, we
would expect to find a total of 3.2 objects in the faintest three magnitude bins. Our detection
of 14 objects in these three bins rules out the constant LF at faint magnitudes hypothesis at the
99.9% confidence level. We conclude that we have indeed measured the turnaround to an increasing
luminosity function for late-L dwarfs as was predicted by Burgasser (2002) and Allen et al. (2003).
The luminosity function derived from the 8 pc sample is shown with our best estimate of the
ultracool dwarf LF in Figure 4.6. Both samples are sensitive to late-M dwarfs, and where the two
measurements overlap, they agree within the 1σ uncertainties. The increasing slope of the bright
half of the LF (0 < MJ < 7) reflects the fact that there are more fainter, less massive stars than
brighter, more massive ones in the Solar Neighborhood. Even though we still expect less massive
objects to significantly outnumber more massive objects well into the low-mass stars regime, we
have measured the LF to be decreasing past MJ = 7 (∼M5). This is due to the fact that low-mass
stars span a large range of magnitudes but a small range of masses. While the mass changes by
118
∼ 0.4 M¯ mag−1 for 0 < MJ < 7, it only decreases ∼ 0.07 M¯ mag−1 for 7 < MJ < 14.
The space density of all L dwarfs is significantly lower than that of M dwarfs while there are
more late-type L dwarfs than that of early-Ls. This is caused by the intrinsically small number of
stellar (hydrogen-burning main sequence) L dwarfs and the fact that brown dwarfs remain on the
L dwarf sequence for a relatively short period of time. The very lowest-mass stars that appear as L
dwarfs (L0–L3) span an extremely small range in mass (0.075 < M¯ < 0.085) and, as a result, are
rare. Almost all brown dwarfs appear as L dwarfs during their early stages of evolution. However,
they evolve relatively quickly through the hotter, early-L dwarf sequence and, as the rate of cooling
decreases at later spectral types, brown dwarfs spend significantly more time as late-L, T, and Y
dwarfs. For example, a 0.070 M¯ brown dwarf remains on the L dwarf sequence for 2.7 Gyr but on
the T sequence for 30 Gyr (∼ 2 Hubble times); a low-mass brown dwarf (25 MJupiter , 0.025 M¯ )
only spends 120 Myr as an L dwarf and 1.5 Gyr as a T dwarf.
4.6.2
Constraints on the Mass Function
Allen, Koerner, & Reid (2004) have used the evolutionary models by Burrows et al. (2001)
to create synthetic luminosity functions where the underlying physical parameters are known—
we are interested in the exponent of a power-law mass function, α, in particular. We compare our
measured ultracool dwarf LF and the T dwarf LF (Burgasser 2002) to the model luminosity functions
in Figure 4.7. Overall, the agreement between the theoretical LFs and the data is quite good—the
models lie within ∼ 2σ of the data points. In addition, the general trend for all realistic values of α
is a turnaround of the LF in the L dwarf regime with a sparser space density of L dwarfs compared
to that of T dwarfs. However, the models appear to be under-predicting the magnitudes of the
features present in the luminosity function. Most striking is that we find the base of the trough of
the LF to be at MJ ∼ 13.5 and the models predict it to be at MJ ∼ 12.5.
Unfortunately, neither our measured L dwarf space densities, nor the currently available T
dwarf data, strongly constrain the mass function. While the best fit is for α = 0.75, the results are
consistent with 0 < α < 1.5 in the substellar regime. Forthcoming revised T dwarf space densities
will likely yield a more robust estimate of α. Not only will these results lend insight into the formation
mechanisms of brown dwarfs, they will also yield the expected space density of as-yet-undiscovered
Y dwarfs.
4.7
Conclusions
We have culled the 2MASS Second Release for objects that appear to be ultracool dwarfs within
20 pc of the Sun. Extensive spectroscopic follow-up has led to the discovery of 94 L dwarfs and
261 late-M dwarfs—56 of these are within 20 pc. Combining these data with previously known nearby
late-type dwarfs, we have used 89 objects to estimate the luminosity function of ultracool dwarfs
119
in the Solar Neighborhood. This work has more than doubled the local census of ultracool dwarfs
and has provided the first robust estimate of the luminosity function of late-type stars and brown
dwarfs. This result is the first measurement of the turnaround of the luminosity function of ultracool
dwarfs at faint magnitudes and is in general agreement with the predictions of evolutionary models.
However, these data are not sufficient to constrain the mass function and space density estimates
for T dwarfs are needed before a robust estimate of α can be obtained. While work clearly remains
to improve the accuracy of the luminosity and mass functions of the low-mass constituents of the
Solar Neighborhood, the picture is quickly coming into focus.
120
8
10
J
12
14
16
18
1.0
1.5
2.0
(J−KS)
2.5
3.0
Figure 4.1.— Status of the follow-up observations of the 2MU2 sample with far-red optical spectra
(triangles), near-infrared spectra (plus signs), and no follow-up (circles). In this paper we only
consider objects with far-red optical data and consider the observational incompleteness for 14.5 <
J < 15.5 (dashed lines). The percentage breakdown of objects with far-red optical data in this
region is listed in Table 4.8.
121
8
1.4
10
1.2
1.0
J
(J−H)
12
0.8
14
0.6
16
1.0
1.5
(J−KS)
2.0
2.5
0.4
0.2
0.4
0.6
(H−KS)
0.8
1.0
Figure 4.2.— Color-magnitude and color-color diagrams of all objects included in the luminosity
function estimate and our selection criteria (solid line). The M7 and M7.5 (plus signs), M8 and
M8.5 (triangles), M9 and M9.5 (squares), and L dwarfs (circles) are also shown.
122
0.0030
0.0025
0.0025
Φ(MJ) (objects pc-3 mag-1)
Φ(MJ) (objects pc-3 mag-1)
0.0030
0.0020
0.0015
0.0010
0.0005
0.0000
10
0.0020
0.0015
0.0010
0.0005
11
12
13
14
0.0000
10
15
MJ
11
12
13
MJ
14
15
Figure 4.3.— The Malmquist corrected luminosity function in J-band with formal Poisson uncertainties (left, solid ) and the J-band luminosity function corrected for observational incompleteness
(dotted, § 4.5.2.1), volume incompleteness (dashed, § 4.5.2.2), and spectral type incompleteness
(dot-dashed, § 4.5.2.3). We also show our best estimate of the luminosity function (right) distinguishing the raw measured densities (unshaded ) from the incompleteness-corrected values (shaded ).
Because early and mid-T dwarfs have MJ values corresponding to the faintest two magnitude bins
(14 < MJ < 15), our measurement is a lower limit on the ultracool dwarf luminosity function.
123
0.006
0.004
0.002
Space Density (objects pc−3 mag−1)
0.000
0.006
0.004
0.002
0.000
0.006
0.004
0.002
0.000
0.006
0.004
0.002
0.000
0.006
0.004
0.002
0.000
8
12
16
20
24
Distance Bin (pc)
28
Figure 4.4.— Uncorrected space densities for two sets of spherical shells for the 2MU2 sample as
a function of MJ . The densities are shown for spherical shells with inner and outer radii from
0–8, 8–12, 12–16, 16–20, 20–24, 24–28 pc (circles) and 0–10, 10–14, 14–18, 18–22, 22-26, 26–30 pc
(crosses). The density for each shell is plotted at the distance of the outer radius (e.g., the density
for the 8–12 pc shell is plotted at 12 pc). The shaded bar shows the overall density for each MJ bin
and the associated formal Poisson uncertainty.
124
1.4
10
1.2
1.0
12
(J−H)
MJ + 1.51
8
0.8
14
0.6
16
1.0
1.5
(J−KS)
2.0
2.5
0.4
0.2
0.4
0.6
(H−KS)
0.8
1.0
Figure 4.5.— Color-magnitude and color-color diagram of M7–L8 dwarfs with parallax measurements
and J < 16.5, and our selection criteria (solid lines). Photometry from the 2MASS second release
is shown where available, otherwise data is from the all-sky release. MJ has been shifted by 1.51 to
reflect our distance limit of 20 pc. Objects that are not selected by our J/(J − K) (diamonds) and
(J − H)/(H − K) (circles) selection criteria are marked in both planes.
125
Φ(MJ) (objects pc-3 mag-1)
0.015
0.010
0.005
0.000
0
5
10
MJ
Figure 4.6.— J-band luminosity function for the 2MU2 (shaded ) and 8 pc samples.
126
15
Φ(MJ) (objects pc-3 mag-1)
α = 0.75
T
M
α = 1.5
Y
Y
L
T
M
L
α = −0.2
Figure 4.7.— Model luminosity functions (solid and dashed lines) constrained by our data for M
and L dwarfs and the T dwarf data from Burgasser (2002). The best-fit model has an underlying
α = 0.75 (left), while the extreme values, α = −0.2 and 1.5 are also consistent with the data (right).
Figure courtesy of Peter Allen.
127
128
0.619
0.720
0.656
0.967
0.629
0.635
0.991
0.659
0.731
J −H
1.034
1.056
1.079
1.614
1.048
1.088
1.495
1.088
1.179
J − KS
2003
2003
2002
2004
2001
2002
2004
2002
2002
Nov 8
Nov 9
Sep 25
Feb 10
Nov 3
Jul 5
Feb 10
Jul 4
Jul 5
Obs.
Date
CT
CT
KP
KP
KP
KP
KP
KP
KP
1.5 m
1.5 m
4m
4m
2.1 m
2.1 m
4m
2.1 m
2.1 m
Telescope
M6–L8 Dwarfs Discovered Within 20 pc
M8
M6
M8
L3.5
M7.5b
M8
L7?c
M7
L0.5
Spectral
Type
11.2±0.2
10.1±0.4
11.2±0.2
12.9±0.2
11.0±0.2
11.2±0.2
14.4±0.4
10.7±0.3
11.9±0.1
MJ
17.2±1.4
19.0±3.3
18.7±1.6
(10.2±1.0)a
18.0±1.8
17.6±1.5
8.4±1.5
13.5±1.6
13.2±0.8
d
(pc)
4
5
1
2, 3
Other
Ref.
Wilson (2002) ST of L6.5 based on NIR data.
References. — (1) Thorstensen & Kirkpatrick (2003); (2) Bessell (1991); (3) Paper I; (4) Wilson (2002); (5) Gizis (2002).
c
While a spectrum of this object is published in Bessell (1991) (it is not mentioned in the text nor assigned a spectral type), it appears to have
been overlooked in the subsequent literature on late-type M dwarfs. To our knowledge, this is the first time it has been formally assigned a spectral
type. However, based on photometry, it was recognized as an ultracool dwarf within 20 pc in Paper I.
b
12.345
11.508
12.518
12.922
12.244
12.379
14.060
11.390
12.458
J
Here dπ = 12.2 pc (Thorstensen & Kirkpatrick 2003).
LHS 2215/LP 429- 12
0123112−692138
0138215−732058
0544115−243301
0700366+315726
0959560+200234
1440229+133923
1515009+484739
1534570−141848
2351504−253736
a
Other
Names
2MASSI
Designation
Table 4.1.
129
0000286−124515
0007078−245804
0010001−203112
0023475−323925
0050244−153818
0053540+500149
0055046−305200
0103079+450929
0107160−151757
0112216−703123
0121525−685518
0131183+380155
0141032+180450
0230155+270406
0241115−032658
0310140−275645
0320171−102612
0355201+143929
0407089−234829
0417474−212919
0436501−180326
0518461−275645
0534584−151143
0605019−234226
0739438+130507
0821501+453201
0953212−101420
1011002+424503
1011395+201903
1028404−143843
1128255+783101
2MASSI
Designation
TVLM 263-71765
Other
Names
13.166
13.147
14.153
12.646
13.765
13.702
13.062
13.704
13.341
13.498
12.885
14.694
13.822
14.255
15.831
15.813
13.865
13.814
13.767
13.854
13.667
15.279
13.151
14.505
13.957
13.469
13.445
13.357
13.860
13.091
13.397
J
0.746
0.684
0.761
0.641
0.673
0.686
0.772
0.745
0.625
0.681
0.676
1.022
0.772
0.770
1.019
1.151
0.747
0.706
0.698
0.728
0.677
0.957
0.636
0.778
0.613
0.720
0.814
0.657
0.783
0.643
0.619
1.223
1.095
1.285
1.002
1.126
1.071
1.137
1.265
1.059
1.128
1.044
1.666
1.315
1.279
1.807
1.873
1.149
1.106
1.148
1.177
1.110
1.651
1.154
1.344
1.214
1.142
1.314
1.056
1.186
1.064
1.007
J − KS
2002
2002
2002
2002
2002
2002
2002
2002
2002
2003
2003
2004
2004
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2004
2003
2004
2003
2003
2002
Jul 7
Sep 26
Sep 25
Sep 28
Sep 26
Sep 25
Sep 26
Sep 25
Sep 26
Nov 9
Nov 8
Feb 12
Feb 11
Sep 26
Sep 27
Sep 28
Sep 26
Sep 28
Sep 26
Sep 26
Sep 25
Sep 28
Sep 25
Sep 27
Sep 26
Feb 10
Apr 22
Feb 10
Apr 22
Apr 23
Jul 8
Obs.
Date
KP
KP
KP
KP
KP
KP
KP
KP
KP
CT
CT
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
KP
CT
KP
CT
CT
KP
2.1 m
4m
4m
4m
4m
4m
4m
4m
4m
1.5 m
1.5 m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
4m
2.1 m
Telescope
M7–L8 Dwarfs Discovered Outside 20 pc
J −H
Table 4.2.
M8.5
M7
L0
M7
L1?
M7.5
M8?
M9
M7
M7?
M7
L4?
L1a
L0?
L0?
L4?
M8
M8
M8?
M8
M7
L0?
M9
L0?
M8
M7.5
L0
M7.5
M8
M7b
M7?
Spectral
Type
11.3±0.2
10.7±0.3
11.7±0.1
10.7±0.3
12.0±0.3
11.0±0.2
11.2±0.4
11.5±0.1
10.7±0.3
10.7±0.5
10.7±0.3
13.1±0.4
12.0±0.1
11.7±0.3
11.7±0.3
13.1±0.4
11.2±0.2
11.2±0.2
11.2±0.4
11.2±0.2
10.7±0.3
11.7±0.3
11.5±0.1
11.7±0.3
11.2±0.2
11.0±0.2
11.7±0.1
11.0±0.2
11.2±0.2
10.7±0.3
10.7±0.5
MJ
23.4±1.7
30.4±3.5
30.5±1.9
24.1±2.8
22.5±3.0
35.3±3.4
24.1±3.9
28.0±1.9
33.2±3.9
35.7±8.3
26.9±3.1
20.9±4.3
23.1±1.6
32.0±3.9
66.1±8.2
35.0±7.3
34.8±2.9
34.0±2.9
33.3±5.4
34.7±2.9
38.6±4.5
51.3±6.3
21.7±1.4
35.9±4.4
36.3±3.1
31.7±3.1
22.0±1.4
30.1±2.9
34.7±2.9
29.6±3.5
34.1±7.9
d
(pc)
2
1
Other
Ref.
130
1147048+142009
1221506−084319
1231214+495923
1303239+360249
1312070+393744
1323521+301433
1332234+154219
1336406+374323
1337311+493836
1357096+554449
1357149−143852
1404449+463429
1405040+291831
1412227+235410
1415202+463659
1434582−233557
1440303+123334
1441045+271932
1453230+154308
1453484+373316
1510295+361948
1536191+330514
1550084+145517
1556502+520656
1557327+175238
1607152+312525
1608246+195747
1612413+173028
1613455+170827
1617003+131349
1711135+232633
2MASSI
Designation
CE 455
DENIS-P J1357149−143852
Other
Names
13.296
13.534
14.639
13.646
14.146
13.681
13.509
14.397
13.739
14.152
12.852
14.352
13.451
13.771
14.185
12.900
14.427
13.022
13.222
13.170
13.963
13.663
14.746
13.883
13.536
12.745
13.521
13.678
13.438
13.328
14.512
J
0.637
0.613
0.949
0.779
0.741
0.608
0.671
0.778
0.668
0.823
0.654
0.814
0.684
0.706
0.776
0.614
0.848
0.609
0.636
0.638
0.736
0.676
0.934
0.707
0.718
0.696
0.712
0.591
0.757
0.569
0.865
J −H
1.041
1.014
1.488
1.136
1.250
1.103
1.054
1.313
1.165
1.304
1.107
1.301
1.009
1.099
1.241
1.025
1.316
1.033
1.019
1.034
1.174
1.056
1.520
1.134
1.087
1.018
1.142
1.096
1.290
1.010
1.460
J − KS
Jul 7
Jul 7
Feb 11
Apr 10
Apr 10
Apr 10
Jul 7
Jul 11
May 14
Apr 10
Mar 13
Jul 11
Jul 7
Jul 7
May 30
Jul 6
Jul 11
Jul 5
Jul 5
Jul 5
Jul 10
Jul 5
Apr 21
Jul 10
Jul 4
Jul 4
May 30
Jul 7
May 30
Jul 4
Sep 27
Obs.
Date
2002
2002
2004
2002
2002
2002
2002
2002
2002
2002
2003
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2003
2002
2002
2002
2002
2002
2002
2002
2002
Table 4.2 (cont’d)
KP 2.1 m
KP 2.1 m
KP 4 m
APO
APO
APO
KP 2.1 m
APO
APO
APO
KP 2.1 m
APO
KP 2.1 m
KP 2.1 m
APO
KP 2.1 m
APO
KP 2.1 m
KP 2.1 m
KP 2.1 m
APO
KP 2.1 m
CT 4 m
APO
KP 2.1 m
KP 2.1 m
APO
KP 2.1 m
APO
KP 2.1 m
KP 4 m
Telescope
M7
M8
L2
M8
L0?
M8.5
M7
L1
L0
M9
M7
L0?
M7
M9
M9
M7
M9
M7
M7.5
M7
M9
M7
L2?
M7
M7.5
M6
M9
M7
M9.5
M7
L0?
Spectral
Type
10.7±0.3
11.2±0.2
12.3±0.2
11.2±0.2
11.7±0.3
11.3±0.2
10.7±0.3
12.0±0.1
11.7±0.1
11.5±0.1
10.7±0.3
11.7±0.3
10.7±0.3
11.5±0.1
11.5±0.1
10.7±0.3
11.5±0.1
10.7±0.3
11.0±0.2
10.7±0.3
11.5±0.1
10.7±0.3
12.3±0.3
10.7±0.3
11.0±0.2
10.1±0.4
11.5±0.1
10.7±0.3
11.6±0.1
10.7±0.3
11.7±0.3
MJ
32.5±3.8
29.9±2.5
29.2±2.3
31.5±2.6
30.4±3.7
29.7±2.2
35.9±4.2
30.2±2.0
25.2±1.6
34.5±2.3
26.5±3.1
33.4±4.1
34.9±4.1
28.9±1.9
35.0±2.3
27.1±3.2
39.1±2.6
28.7±3.4
28.3±2.8
30.7±3.6
31.6±2.1
38.5±4.5
30.7±4.8
42.6±5.0
32.7±3.2
33.5±5.8
25.8±1.7
38.8±4.5
23.3±1.5
33.0±3.8
36.0±4.4
d
(pc)
4
3
Other
Ref.
131
Strong flare object.
13.612
13.278
15.320
14.075
14.800
13.195
14.863
13.006
13.584
14.949
13.666
14.397
13.582
13.334
14.526
13.411
13.609
14.850
13.296
12.868
13.062
J
0.659
0.609
1.093
0.693
0.867
0.608
0.895
0.713
0.707
1.033
0.709
0.819
0.680
0.609
0.797
0.698
0.677
0.986
0.640
0.693
0.705
J −H
1.112
1.039
1.959
1.210
1.441
1.060
1.480
1.158
1.044
1.801
1.073
1.388
1.122
1.088
1.419
1.129
1.068
1.621
1.091
1.146
1.117
J − KS
2002
2002
2002
2002
2003
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
Sep 25
Jul 4
Sep 27
Jul 11
Apr 21
Jul 4
Sep 26
Jul 4
Jul 4
Sep 26
Jul 11
Sep 25
Jul 5
Jul 5
Sep 26
Jul 5
Jul 6
Sep 26
Jul 5
Jul 6
Sep 25
Obs.
Date
KP 4 m
KP 2.1 m
KP 4 m
APO
CT 4 m
KP 2.1 m
KP 4 m
KP 2.1 m
KP 2.1 m
KP 4 m
APO
KP 4 m
KP 2.1 m
KP 2.1 m
KP 4 m
KP 2.1 m
KP 2.1 m
KP 4 m
KP 2.1 m
KP 2.1 m
KP 4 m
Telescope
M7
M7
L5?
M8
L1?
M7
L2?
M7.5
M7.5
L4?
M7?
L0?
M8.5
M9
L1?
M7.5
M8
L4?
M8
M7
M8.5
Spectral
Type
10.7±0.3
10.7±0.3
13.6±0.5
11.2±0.2
12.0±0.3
10.7±0.3
12.3±0.3
11.0±0.2
11.0±0.2
13.1±0.4
10.7±1.0
11.7±0.3
11.3±0.2
11.5±0.1
12.0±0.3
11.0±0.2
11.2±0.2
13.1±0.4
11.2±0.2
10.7±0.3
11.3±0.2
MJ
37.6±4.4
32.3±3.8
22.5±4.9
38.4±3.2
36.3±4.8
31.1±3.6
32.4±5.0
25.6±2.5
33.4±3.3
23.5±4.8
38.6±17.9
34.1±4.1
28.3±2.1
23.6±1.5
32.0±4.2
30.9±3.0
31.0±2.6
22.4±4.6
26.8±2.2
26.7±3.1
22.3±1.6
d
(pc)
3
5
Other
Ref.
References. — (1) Wilson (2002);(2) Tinney, Reid, Gizis, & Mould (1995); (3) Phan-Bao et al. (2001); (4) Ruiz, Wischnjewsky, Rojo, & Gonzalez (2001);
(5) Lodieu, Scholz, & McCaughrean (2002).
Wilson (2002) ST of L4.5 based on NIR data.
b
DENIS-P J2353594−083331
SSSPM 23101853−1759094
Other
Names
a
1717045+150953
1923381−330841
2002507−052152
2025196−255048
2026158−294312
2035203−311008
2041428−350644
2047247+142152
2123311−234518
2158045−155009
2308099−313122
2310185−175909
2323134−024435
2329479−160755
2330225−034718
2337166−093324
2341286−113335
2344062−073328
2346547−315353
2352050−110043
2353594−083331
2MASSI
Designation
Table 4.2 (cont’d)
132
LP 763- 14
LP 985- 98
LP 699- 64
DENIS-P J2107247−335733
LHS 2980
Other
Names
References. — (1) Phan-Bao et al. (2001).
0017185−040606
0107590−200423
0355403−112310
0411063+124748
0510239−280053
0544167−204909
1144050+604348
1222143+565559
1239285+134142
1242271+445140
1312393+183559
1411392+602447
1414153−141822
1436418−153048
1450366+472357
1529456+821532
1628170+133420
1631136+192200
1734419+123105
2002066−023314
2003438−144917
2040269−152316
2107247−335733
2208546−244911
2215171−045919
2229444−192324
2309142−353159
2336142−093606
2338541−124618
2340477+462318
2353081−082916
2MASSI
Designation
J
0.642
0.614
0.645
0.652
0.646
1.002
0.598
0.697
0.705
0.615
0.654
0.684
0.559
0.626
0.663
0.610
0.662
0.724
0.715
0.779
0.718
0.761
0.613
0.707
0.688
0.696
0.684
0.635
0.557
0.680
0.651
J −H
1.025
1.024
1.010
1.015
1.010
1.515
1.015
1.099
1.042
1.088
1.115
1.016
1.014
1.010
1.012
1.032
1.004
1.052
1.031
1.093
1.029
1.089
1.056
1.016
1.004
1.025
1.049
1.094
1.014
1.001
1.017
J − KS
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
Jul 7
Sep 27
Sep 27
Sep 28
Sep 28
Sep 25
Jul 8
Jul 8
Jul 7
Jul 8
Apr 10
Jul 7
Jul 6
Jul 6
Jul 5
Jul 5
Jul 4
Jul 4
Jul 4
Jul 5
Jul 4
Jul 4
Jul 7
Jul 4
Jul 4
Jul 4
Jul 3
Jul 5
Jul 5
Jul 6
Jul 6
Obs.
Date
KP 2.1 m
KP 4 m
KP 4 m
KP 4 m
KP 4 m
KP 4 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
APO
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
Telescope
M6.5
M6
M6
M6
M4
M5
M6
M6
M6
M5
M5
M6
M6
M5
M6
M5
M5
M5
M1
M3
M5
M2
M6
M6
M6
M3
M5
M6.5
M6.5
M6
M5
Spectral
Type
Early-Type M Dwarfs Discovered Outside 20 pc
12.485
12.817
12.947
12.777
12.964
14.394
12.290
13.662
13.595
13.592
13.238
13.461
13.499
13.128
13.374
13.437
11.674
13.457
13.095
10.502
13.580
13.656
12.213
12.897
13.441
13.512
12.035
13.393
12.181
13.320
13.274
Table 4.3.
46.6±8.0
47.5±8.2
10.1±0.4
10.1±0.4
10.5±0.3
10.5±0.3
10.1±0.4
10.1±0.4
10.1±0.4
10.1±0.4
38.7±5.5
22.1±3.1
43.7±7.5
26.2±4.5
36.0±6.2
46.2±8.0
44.8±7.7
27.2±4.7
51.2±8.8
49.6±8.6
10.1±0.4
10.1±0.4
10.1±0.4
10.1±0.4
25.5±3.6
34.7±6.0
36.8±6.3
34.0±5.9
d
(pc)
10.5±0.3
10.1±0.4
10.1±0.4
10.1±0.4
MJ
1
Other
Ref.
133
DENIS-P J0436278−411446
Other Name
13.063
13.105
12.873
15.392
J
0.699
0.689
0.741
0.975
J −H
1.108
1.043
1.135
1.647
J − KS
Low Gravity Objects
2002
2003
2002
2002
Sep 25
Nov 8
Sep 27
Sep 27
Obs.
Date
KP
CT
KP
KP
4m
1.5 m
4m
4m
Telescope
(M7)
(M9)
(M7)
(L1)
Spectral
Typea
1
Other
Ref.
References. — (1) Phan-Bao et al. (2003).
a
The spectral types should only be used as an estimate of the shape of the spectrum since all of these objects have spectral
features indicative of youth.
0003422−282241
0436278−411446
0557509−135950
2213449−213607
2MASSI
Designation
Table 4.4.
Table 4.5. Spectroscopically Confirmed Giants
2MASSI
Designation
J
J −H
J − KS
0057017+450949
0426258+154502
0712435+395831
1119051+700609
1340371−011604
1550248+821009
1741494+152317
1750217+132703
1804046+220610
1807133+150212
1817475+201534
1843260+405033
1923327−305502
1927415−323251
1936154−343109
1941178−262716
1959007−223323
2000171−270537
2002404−294746
2005582−012730
2007596−043924
2041113+000747
2102375+184551
2124586−012325
2133408+292531
2157407−001650
2222068+220849
2233559+403935
2235440+194245
2237158+372132
2238182+411355
2350294+451749
10.002
11.860
9.156
10.276
13.492
9.667
9.173
9.128
9.260
9.108
9.825
9.275
9.222
9.008
10.837
10.525
9.147
9.096
9.157
9.314
9.576
9.220
9.674
9.975
9.257
13.662
9.698
9.792
13.501
9.006
10.260
10.167
0.776
0.695
0.743
0.741
0.619
0.778
0.758
0.759
0.788
0.799
0.798
0.780
0.756
0.769
0.780
0.835
0.720
0.771
0.720
0.915
0.914
0.726
0.796
0.782
0.789
0.773
0.717
0.785
0.703
0.788
0.800
0.833
1.202
1.021
1.119
1.096
1.106
1.095
1.071
1.063
1.098
1.109
1.118
1.144
1.083
1.109
1.111
1.246
1.038
1.260
1.070
1.481
1.456
1.026
1.203
1.121
1.093
1.136
1.158
1.122
1.030
1.111
1.100
1.222
134
Obs.
Date
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2003
2002
2002
2002
2003
2002
2003
2002
2003
2003
2002
2003
2002
2002
Jul 8
Sep 26
Sep 25
Jul 8
Jul 7
Jul 10
Sep 25
Jul 6
Jul 3
Sep 25
Sep 25
Jul 3
Jul 3
Jul 5
Sep 25
Jul 5
Jul 5
Jul 5
Jul 9
Jul 3
Jul 3
Sep 26
Apr 20
Jul 3
Jul 9
Sep 25
Jul 9
Jul 9
Jul 4
Jul 10
Sep 25
Jul 6
Telescope
KP 2.1 m
KP 4 m
KP 4 m
KP 2.1 m
KP 2.1 m
APO
KP 4 m
KP 2.1 m
KP 2.1 m
KP 4 m
KP 4 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 4 m
KP 2.1 m
KP 2.1 m
KP 2.1 m
KP 4 m
KP 2.1 m
KP 2.1 m
KP 4 m
CT 4 m
KP 2.1 m
KP 4 m
KP 4 m
KP 4 m
KP 4 m
KP 2.1 m
KP 4 m
KP 4 m
KP 2.1 m
Spectral
Type
M8
M5
K5
M4
<K5
M7
M3
M7
M3
M3
K5
M3
M5
M5
M0
M5
M1
M7
M3
M6
M5
M0
M7
M3
M0
M4
M8
M0
K5
M3
M0
M4
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
III
Table 4.6.
Spectroscopically Confirmed Carbon Stars
2MASSI
Designation
J
J −H
J − KS
0027523−705231
0044155−711540
0046008−752112
0107522−692136
0126348−703947
0148078−715521
0156260+512521
0224319+372933
0554397−144658
0606344+731027
1015259−020431
1504553+354757
1941285−323338
2002292−245258
2252361+474125
13.368
13.398
13.182
13.153
12.817
12.471
9.395
11.498
12.731
9.397
14.045
12.000
10.865
9.199
9.624
1.382
1.189
1.071
1.288
1.478
1.271
1.143
1.619
0.767
0.986
1.184
1.322
0.959
0.774
1.073
2.320
2.006
1.922
2.177
2.494
2.199
1.713
2.775
1.083
1.519
2.058
2.323
1.412
1.077
1.633
135
Obs.
Date
2003
2003
2003
2003
2003
2003
2003
2003
2002
2002
2003
2003
2002
2002
2003
Nov 9
Nov 9
Nov 9
Nov 9
Nov 9
Nov 10
Jul 9
Jul 9
Sep 27
Sep 25
Apr 22
Mar 14
Sep 25
Jul 3
Jul 9
Telescope
CT
CT
CT
CT
CT
CT
KP
KP
KP
KP
CT
KP
KP
KP
KP
1.5 m
1.5 m
1.5 m
1.5 m
1.5 m
1.5 m
4m
4m
4m
4m
4m
2.1 m
4m
2.1 m
4m
136
0019262+461407
0019457+521317
0024246−015819
0027559+221932
0109511−034326
0123112−692138
0144353−071614
0148386−302439
0205293−115930A
0205293−115930B
0213288+444445
0248410−165121
0251148−035245
0253202+271333
0255035−470050
0320596+185423
0331302−304238
0339352−352544
0351000−005244
0417374−080000
0423485−041403
0429184−312356A
0429184−312356B
0435161−160657
0439010−235308
0440232−053008
0443376+000205
0445538−304820
0517376−334902
0523382−140302
0544115−243301
0652307+471034
0700366+315726
0741068+173845
0746425+200032A
0746425+200032B
0752239+161215
0818580+233352
0825196+211552
0835425−081923
0847287−153237
0853362−032932
0859254−194926
0908380+503208
2MASSI
Designation
Other
Names
LHS 2065/LP 666- 9/GJ 3517
LP 423- 31
LHS 1937/LP 423- 14
DENIS-P J0517-3349
LP 655- 48
SDSS 0443+0002
LP 775- 31
SDSS J0423-0414
DENIS-P J0255-4700
LP 412- 31
LP 888- 18
LP 944- 20/BRI 0337-3535
LHS 1604/LP 593- 68/GJ 3252
LP 771-21/BR 0246-1703
DENIS-P J0205.4-1159A
DENIS-P J0205.4-1159B
12.609
12.820
11.860
10.608
11.695
12.335
14.187
12.282
14.581
14.581
13.512
12.557
13.082
12.504
13.225
11.744
11.371
10.748
11.262
12.166
14.452
10.887
10.887
10.396
14.413
10.681
12.517
13.409
11.995
13.117
12.518
13.545
12.922
11.995
11.742
11.742
10.831
12.137
15.116
13.149
13.519
11.185
15.505
14.564
J
0.676
0.748
0.740
0.638
0.774
0.619
1.183
0.641
0.991
0.991
0.740
0.701
0.821
0.667
1.036
0.701
0.672
0.731
0.670
0.654
1.010
0.680
0.680
0.616
1.045
0.696
0.713
0.835
0.672
0.896
0.656
1.175
0.967
0.633
0.743
0.743
0.639
0.635
1.328
1.195
0.892
0.717
1.067
1.098
J −H
1.135
1.204
1.280
1.047
1.277
1.034
1.904
1.038
1.599
1.599
1.269
1.148
1.429
1.049
1.698
1.172
1.095
1.223
1.071
1.112
1.516
1.086
1.086
1.060
1.606
1.124
1.350
1.425
1.176
1.486
1.079
1.858
1.614
1.026
1.255
1.255
1.012
1.007
2.071
1.993
1.465
1.213
1.778
1.646
J − KS
M8
M9
M9.5
M8
M9
M8
L5
M7.5
L7
L7
L1.5
M8
L3
M8
L8
M8
M7.5
M9
M7.5
M7.5
L7.5
M7.5
L1
M7
L6.5
M7
M9.5
L2
M8
L2.5
M8
L4.5
L3.5
M7
L0.5
L2
M7
M7
L7.5
L5
L2
M9
L6
L5
Spectral
Type
11.2±0.2
11.5±0.1
11.55±0.1
11.2±0.2
11.5±0.1
11.2±0.2
13.6±0.2
11.0±0.2
13.85±0.07
13.85±0.07
12.1±0.2
11.5±0.19
12.7±0.2
11.2±0.2
14.8±0.1
10.94±0.04
11.0±0.2
12.27±0.05
10.43±0.06
11.0±0.2
13.55±0.07
11.0±0.2
12.0±0.1
10.7±0.3
14.2±0.2
10.7±0.3
11.6±0.1
12.3±0.2
11.2±0.2
12.5±0.2
11.2±0.2
13.3±0.2
12.49±0.06
10.7±0.3
11.88±0.03
12.28±0.03
10.7±0.3
10.7±0.3
14.98±0.05
13.6±0.2
12.3±0.2
11.53±0.04
14.0±0.2
13.6±0.2
MJ
19.5±1.6
18.7±1.2
11.55±0.53
7.8±0.6
11.1±0.7
17.2±1.4
13.4±1.5
18.4±1.8
19.76±0.59
19.76±0.59
18.7±1.4
16.23±1.42
12.1±1.1
18.6±1.5
4.9±0.3
14.51±0.13
12.1±1.2
4.97±0.10
14.66±0.39
17.4±1.7
15.17±0.39
11.4±1.1
11.4±1.1
8.6±1.0
10.8±1.1
9.8±1.1
15.3±1.0
16.6±1.3
14.7±1.2
13.4±1.1
18.7±1.6
11.1±1.2
12.2±0.3
17.9±2.1
12.21±0.04
12.21±0.04
10.5±1.2
19.1±2.2
10.66±0.11
8.3±0.9
17.5±1.4
8.53±0.11
19.8±2.2
15.9±1.8
d
(pc)
ST
ST
Parallax
ST
ST
ST
ST
ST
Parallax
Parallax
ST
Parallax
ST
ST
ST
Parallax
ST
Parallax
Parallax
ST
Parallax
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
Parallax
ST
Parallax
Parallax
ST
ST
Parallax
ST
ST
Parallax
ST
ST
Source
Ref.
Objects Used to Estimate the Luminosity Function (The 20 pc 2MU2 Sample)
BRI 0021-0214
LHS 1060/LP 349-25
LP 647-13
Table 4.7.
1
1
2
3, 4
1, 5, 6
7
1, 8
1
9
10
1
5, 11
1, 12
4
13
4, 5
1, 5, 6
5, 11
1, 3, 14
1
15
1
16
1, 5, 6
1
1, 5, 6
12, 15
1
1, 17
1, 12
7
1
18
3, 19
20
21
1, 5
4
20
1
1
3, 22
1
1, 23
Discovery
Ref.
137
0959560+200234
1006319−165326
1010148−040649
1016347+275149
1024099+181553
1045240−014957
1058478−154817
1104012+195921
1108307+683017
1121492−131308
1124048+380805
1213033−043243
1224522−123835
1253124+403403
1300425+191235
1305401−254106
1309218−233035
1332244−044112
1356414+434258
1403223+300754
1411213−211950
1438082+640836
1440229+133923
1456383−280947
1506544+132106
1507277−200043
1507476−162738
1515009+484739
1521010+505323
1534570−141848
1546054+374946
1658037+702701
1721039+334415
1757154+704201
1807159+501531
1835379+325954
1843221+404021
2037071−113756
2057540−025230
2104149−103736
2224438−015852
2237325+392239
2MASSI
Designation
G 216-7B
LHS 3406/LP 229- 30
LP 44-162
LHS 3003/LP 914-54/GJ 3877
LP 220- 13
Kelu-1
CE 303
BR 1222-1221
LHS 2645/LP 219- 8
LHS 2397a/LP 732- 94
SDSS J1045-0149
DENIS-P J1058-1548
LHS 2243/LP 315- 53
LHS 2215/LP 429- 12
LP 789- 23
Other
Names
12.244
12.041
15.503
11.951
12.242
13.129
14.184
14.462
13.139
11.929
12.710
14.672
12.564
12.177
12.710
13.417
11.769
12.342
11.704
12.691
12.442
12.923
12.379
9.957
13.414
11.718
12.822
14.060
11.997
11.390
12.437
13.309
13.584
11.446
12.963
10.273
11.299
12.284
13.123
13.846
14.052
13.346
J
0.629
0.620
1.108
0.657
0.664
0.759
0.944
0.984
0.912
0.672
0.682
0.995
0.733
0.620
0.641
1.030
0.682
0.591
0.673
0.683
0.619
0.895
0.635
0.630
1.002
0.668
0.920
0.991
0.655
0.659
0.644
0.766
0.662
0.604
0.814
0.691
0.632
0.665
0.850
0.887
1.249
0.664
J −H
1.048
1.041
1.908
1.005
1.037
1.319
1.673
1.486
1.539
1.206
1.138
1.669
1.193
1.004
1.105
1.691
1.103
1.046
1.070
1.065
1.122
1.350
1.088
1.040
1.666
1.064
1.520
1.495
1.075
1.079
1.018
1.390
1.110
1.073
1.356
1.119
1.030
1.024
1.375
1.491
2.035
1.192
J − KS
Table 4.7 (cont’d)
M7.5
M7.5
L6
M7.5
M8
L1
L3
L4
L0.5
M8.5
M8.5
L5
M9
M7.5
L1
L2
M8
M7.5
M7
M8.5
M9
M9.5
M8
M7
L3
M7.5
L5
L7
M7.5
M7
M7.5
L1
L3
M7.5
L1.5
M8.5
M8
M8
L1.5
L3
L4.5
M9.5
Spectral
Type
11.0±0.2
11.0±0.2
14.0±0.2
11.0±0.2
11.2±0.2
12.0±0.1
12.99±0.05
13.1±0.2
11.9±0.1
11.15±0.07
11.3±0.2
13.6±0.2
11.40±0.14
11.0±0.2
12.0±0.1
12.06±0.09
11.2±0.2
11.0±0.2
10.7±0.3
11.3±0.2
11.5±0.1
11.6±0.1
11.2±0.2
10.94±0.05
12.7±0.2
11.0±0.2
13.50±0.03
14.4±0.4
11.0±0.2
10.7±0.3
11.0±0.2
11.97±0.04
12.7±0.2
11.0±0.2
12.1±0.2
11.51±0.03
10.55±0.04
11.2±0.2
12.1±0.2
12.7±0.2
13.78±0.04
11.96±0.09
MJ
18.0±1.8
16.4±1.6
19.8±2.2
15.8±1.5
16.5±1.4
16.8±1.1
17.33±0.30
18.8±2.0
18.0±1.1
14.29±0.43
19.0±1.4
16.7±1.8
17.06±1.11
17.5±1.7
13.9±0.9
18.66±0.70
13.3±1.1
18.9±1.8
15.6±1.8
18.8±1.4
15.7±1.0
18.4±1.1
17.6±1.5
6.37±0.12
14.1±1.3
14.2±1.4
7.33±0.03
8.4±1.5
16.1±1.6
13.5±1.6
19.7±1.9
18.55±0.24
15.2±1.4
12.5±1.2
14.6±1.1
5.67±0.02
14.14±0.16
16.8±1.4
15.7±1.1
17.2±1.6
11.35±0.14
18.89±0.69
d
(pc)
ST
ST
ST
ST
ST
ST
Parallax
ST
ST
Parallax
ST
ST
Parallax
ST
ST
Parallax
ST
ST
ST
ST
ST
ST
ST
Parallax
ST
ST
Parallax
ST
ST
ST
ST
Parallax
ST
ST
ST
Parallax
Parallax
ST
ST
ST
Parallax
Parallax
Source
Ref.
3, 24
1, 5, 17
1
3, 4
4
1, 15
9
1
4
3, 25
1
1
26
3, 27
4
28
1, 29, 30
1
1, 5
4
1
1
7
3, 31
4
1
20
1, 12
1
7, 30
4
4
1
4, 5
1, 12
32, 33
3, 22
1
1
1
20
34
Discovery
Ref.
138
LP 523- 55
2306292−050227
2349489+122438
2351504−253736
11.372
12.615
12.458
J
0.654
0.663
0.731
J −H
1.084
1.053
1.170
J − KS
M8
M8
L0.5
Spectral
Type
11.2±0.2
11.2±0.2
11.9±0.1
MJ
11.0±0.9
19.6±1.6
13.2±0.8
d
(pc)
ST
ST
ST
Source
Ref.
4
4, 5
7
Discovery
Ref.
References. — (1) Paper V; (2) Irwin, McMahon, & Reid (1991); (3)Luyten (1979); (4) Gizis et al.
(2000); (5) Luyten (1979); (6) Paper III; (7) This Paper; (8) Kendall et al. (2003); (9) Delfosse et al.
(1997); (10) Koerner et al. (1999); (11) Tinney (1996); (12) Wilson (2002); (13) Martı́n et al. (1999);
(14) Reid, Hawley, & Gizis (1995); (15) Hawley et al. (2002); (16) Siegler & Close (2004); (17) PhanBao et al. (2003); (18) Thorstensen & Kirkpatrick (2003); (19) Gizis & Reid (1997); (20) Kirkpatrick et
al. (2000); (21) Reid et al. (2001); (22) Monet et al. (1992); (23) Knapp et al. (2004); (24) Bessell (1991);
(25) Liebert, Boroson, & Giampapa (1984); (26) Tinney, Mould, & Reid (1993); (27) Kirkpatrick,
Henry, & McCarthy (1991); (28) Ruiz, Leggett, & Allard (1997); (29) Ruiz, Wischnjewsky, Rojo,
& Gonzalez (2001); (30) Gizis (2002); (31) Kirkpatrick, Henry, & Simons (1995); (32) Paper IV;
(33) Lépine, Shara, & Rich (2002); (34) Kirkpatrick et al. (2001).
Other
Names
2MASSI
Designation
Table 4.7 (cont’d)
Table 4.8.
Percentage of Optical Follow-up Observations Completed
J Range
Percentage Observed
14.5–15.0
15.0–15.5
15.5–16.0
16.0–16.5
72.7
63.6
38.1
22.2
139
Table 4.9.
MJ
Bin
not
affected
13.0–13.5
13.5–14.0
14.0–14.5
14.5–15.0
2
3
2
1
Corrections for Observational Incompleteness
14.5 < J < 15
obs.
correction
1
3
0
1
0.375
1.123
···
0.375
15 < J < 15.5
obs.
correction
0
4
0
0
140
···
2.286
···
···
obs.
3
10
2
2
Total
corrected
3.375
13.411
2
2.375
Chapter 5
Future Work and Summary
In this final chapter we describe the tasks that remain and new projects that have been spawned.
5.1
5.1.1
Completing the Census
Finish Follow-up Observations of 2MU2 Sample
There are only fifteen objects in the 2MU2 sample with no follow-up observations. Of these,
seven are at very southern declinations near the Large or Small Magellanic Clouds and are likely
giants or carbon stars. Eight (all with 15.9 < J < 17) will be targeted for near-infrared spectroscopic
observations. The extreme southern objects will be followed-up during future CTIO 4 m observing
runs. However, it is unlikely that any of these objects will be ultracool dwarfs within 20 pc.
In addition, there are twelve objects which have been confirmed as L dwarfs with near-infrared
spectra because they were too faint for 4-m far-red follow-up. However, because of the complications
with estimating spectral types with near-infrared data, the distances to these objects are highly
uncertain. We have proposed to obtain far-red spectra of these objects with Gemini in order to get
reliable spectral type and distance estimates.
5.1.2
2MASS All-Sky Release
All of the results presented in this dissertation are based on data from the 2MASS Second
Incremental Release, which was made public in 2000 March, and covers 47% of the sky. In 2003
March, the All-Sky Release was made available—we obtained the first follow-up observations of those
data in the same month. With a more stringent (J − K) and galactic latitude cut ((J − K) > 1.06,
|b| > 15◦ ), the data we culled from the All-Sky Release has proven to be fertile ground. Of the initial
1018 objects in the sample (dubbed 2MUF), 546 have been eliminated based on visual inspection, 41
are known nearby late-type dwarfs, we have observed 354, and 77 are targeted for future observations.
141
In the sample of 354 targets, we have identified 47 previously unrecognized M7–L8 dwarfs within
20 pc. We expect to submit these first discoveries of ultracool dwarfs for publication later this year.
As a side note, Finlay Mungall, a Wharton undergraduate with a strong interest in astronomy,
played a major role in compiling and reducing this data.
5.1.3
Companion Searches
Brown dwarf binaries provide strong constraints on the evolutionary properties of these lowmass objects. They are assumed to be coeval and, because they also have very small separations
(< 15 AU), they provide opportunities to measure the mass of the system dynamically. In addition,
most ultracool binaries found have near equal masses. If this a true property of ultracool dwarf
binary systems, rather than a selection effect, then it provides a significant constraint on formation
mechanisms.
Many of the objects discovered in the 2MU2 sample are likely to be unresolved binaries. The
binary fraction of ultracool dwarfs has been estimated to be about ∼15% while only 3.5% of the
objects we have identified within 20 pc have known companions. In addition, we are biased towards identifying multiple systems because they appear brighter and are more likely to fall into our
magnitude-limited sample. We are involved in several efforts to uncover the unrecognized multiple
systems in the 2MU2 sample.
Laird Close and Nick Siegler have observed twelve of the brightest, nearest objects in the 2MU2
sample with adaptive optics (AO) systems on Subaru and ESO’s Very Large Telescope (VLT). Two
of the twelve were revealed to be binary (Siegler & Close 2004). In addition, the objects are part of
proposed observations using Gemini South and the new Laser Guide Star AO (LGS-AO) system on
Keck. Because the previous AO configurations use the primary as the guide star, these efforts have
been restricted to the brightest and earliest objects in the sample. The Keck LGO-AO system will
provide the first opportunity to probe around the cooler systems with ground based observations.
In order to uncover the cooler systems, we are using NICMOS on the Hubble Space Telescope
(HST) to search for companions to sixty-eight L dwarfs within 20 pc. These observations will be
sensitive to very close companions (> 1.6 AU) and to very cool secondaries such as T and Y dwarfs.
5.2
Understanding Brown Dwarf Atmospheres
Geballe et al. (2002) has proposed a near-infrared classification scheme for L dwarfs. However,
it has been widely shown that the spectral features in the near infrared are more sensitive to the
properties of condensate clouds in brown dwarf atmospheres rather than the physical properties of
the object (e.g., temperature and gravity). As a result, the far-red and near-infrared spectral types
of the same object can differ by as much as three subtypes (Knapp et al. 2004). Further complicating
this issue are that L dwarfs are significantly brighter in the near-infrared than in the optical and
142
thus near-infrared observations can be obtained with a smaller telescope. However, regardless of the
ease of working in the near-infrared, spectral types based on these data should be used with extreme
caution, if at all. Unfortunately, the use of near-infrared spectral types is wide-spread and the urge
to use them interchangeably with far-red types is hard to resist since very few objects have data in
both wavelength regimes.
We have compiled an extensive library of far-red and near-infrared spectra for many of the
nearest L dwarfs in both the 2MU2 and 2MUF samples. This collection of data is ideal for definitively
demonstrating the full extent of the problems with mixing and matching spectral types from different
wavelength ranges. We will use this data set to make detailed comparisons of individual object’s
features in both the far-red and near-infrared with the goal of linking the two systems. However, it
is likely that the systems are unreconcilable and that spectral types should be based on the far-red
part of the spectrum, as it was originally defined (Kirkpatrick et al. 1999), and that near-infrared
spectra should only be used to give rough characterizations of L dwarfs.
5.3
Discovering the Lowest-Mass Brown Dwarfs with Spitzer
While there has been much recent progress in the search for L and T dwarfs, probing even
cooler temperatures is uncharted territory. These objects, tentatively dubbed Y dwarfs, theoretically
range in temperature from 130 to 800 K and have masses between 1 and 25 Jupiter masses. Their
properties in relation to late-type stars and brown dwarfs are illustrated in Figure 5.1. No isolated
objects fitting this description have been found, however, the search has not yet begun in earnest.
Using archival data from the Spitzer Space Telescope, we will carry out the first search for Y dwarfs
in the field.
The Spitzer Wide-area Infrared Extragalactic Survey (SWIRE) Legacy program will provide
a dataset which will be ideal to cull for both T and Y dwarfs. Even though the primary science
mission of this program is to study cosmology and galaxy formation at moderate to high redshifts,
there are many aspects of its observing strategy that make it very suitable to search for cool brown
dwarfs in the near future:
• Fields are at high galactic latitude so crowding will not be a problem.
• Observations are deep, reaching to 18.7 magnitudes at 4.5 microns (very close to M band)
which should allow us to probe to temperatures well into the Y dwarf regime.
• Large sky coverage with 70 sq. deg. in total.
• As a Legacy program, the observations are taken within the first year of the mission and the
data become public almost immediately with no proprietary period.
Assuming a flat (α = 1) mass function, we anticipate finding hundreds of T dwarfs and tens of
Y dwarfs in the SWIRE dataset using the photometry acquired with the InfraRed Array Camera
143
(IRAC). The IRAC colors are well positioned to identify T and Y dwarfs with the methane bands
(3.6 and 8 µm), the SED peak (4.5 µm), and the water band (5.6 µm).
It is likely that the Spitzer GTO programs will uncover a small number of cool-T and Y dwarfs
as companions to known nearby stars. Combined with our results from the field, these initial
discoveries will map out the regions of infrared color space in which Y dwarfs reside and characterize
any possible contaminates. These advancements will enable a more targeted search through other
Spitzer archival data. In addition, this work will be the precursor to the proposed Wide-field Infrared
Survey Explorer (WISE). This is a NASA MidEx mission and is currently in extended Phase A study
and is proposed to launch at the end of 2007. Just as 2MASS revolutionized L dwarf astronomy,
WISE should result in an avalanche of discoveries of T and Y dwarfs. The research proposed here
will identify a vital representative set of reference objects and is essential to test the theoretical
spectral predictions.
This work is among the first steps necessary to compare the properties of very low-mass brown
dwarfs and planets. The T and Y dwarfs uncovered during this program will yield a luminosity
function that will constrain the field mass function to unprecedented low masses. This will be a
critical test to differentiating between stars and planets since if their mass functions are different, it
is very likely that they have different formation mechanisms.
5.4
Summary
In this dissertation, we have described our efforts to study low-mass stars and brown dwarfs
in the Solar Neighborhood. This work has resulted in many new discoveries, in particular, we have
more than doubled the local census of ultracool dwarfs. We have also made the first measurement
of the ultracool dwarf luminosity function and its turnaround at fainter magnitudes—an important
confirmation of theoretical predictions. In addition, we have created a sample of objects which is
ideal to study the detailed properties of these objects and we are leading the effort to discover the
links between stars, brown dwarfs, and planets.
144
Figure 5.1.— Artist conception of M, L, and T Dwarfs and Jupiter. The drawing is to scale and
physical characteristics are labeled. Illustration by Robert Hurt and courtesy of Davy Kirkpatrick.
145
146
Appendix A
The Brightest Sources
A.1
Introduction
As discussed in the text, 588 sources in our ultracool sample have magnitudes brighter than
J = 9. Figure A.1 shows the distribution of those stars on the celestial sphere and in the near-infrared
color-magnitude and color-color planes. Sources with galactic latitudes in the range −10◦ < b < 10◦
were excluded ab initio. The fiducial dwarf and giant sequences are plotted in the JHKS two-color
diagram, together with data for L dwarfs from Kirkpatrick et al. (1999). Note that we require
sources to have (J − KS ) > 1.0 and (H − KS ) > 0.3; approximately 15% of known L dwarfs have
colors outside the limits bounded by the present search criteria.
A.2
Identifications
All 588 sources were cross-referenced against the SIMBAD database using a search radius of
2.0 arcminutes centered on the 2MASS position. As discussed in the text, four stars are confirmed
as nearby dwarfs: G 180-11, G 139-3, Gl 866ABC and BD-01 3925D. The results for the remaining
584 candidates are as follows:
IRAS sources. — One hundred seventeen 2MASS candidates lie within 10 to 15 arcseconds of a
source from the IRAS catalog; given the positional uncertainties of the IRAS astrometry, plus
the expectation that IRAS sources should be red in (J − KS ), these are highly likely to be the
correct identification for the 2MASS source. The overwhelming majority of these sources are
expected to be dusty asymptotic giant branch stars (types M, S and C) or red supergiants.
These sources are listed in Table A.1. We list J magnitudes for extremely bright sources where
2MASS H and/or KS photometry is unavailable, using “:” to denote uncertain measurements.
Most of these sources lie close to the Plane, as expected for young giants or luminous AGB
stars.
147
Stellar sources. — One hundred thirty eight candidates lie within 2 to 3 arcseconds of stars
listed in either the Henry Draper, Bonner Durchmusterung, Cape Durchmusterung, Cape
Photographic Durchmusterung, Guide Star Catalog, or PPM catalogues. Data for these sources
are given in Table A.2. Most of the sample have colors close to the giant sequence in the JHKS
plane, with approximately fifteen stars overlapping with the L dwarf distribution. The latter
stars are likely to be carbon stars.
Carbon stars. — Thirteen stars in the sample are classed as carbon stars in SIMBAD. Figure A.2
shows their distribution on the sky and in the near-infrared plane—there is obvious overlap
with the L dwarf distribution in the two-color diagram. Data for these stars are listed in Table
A.3.
Mira variables. — Eighty stars are identified as Miras—M-type long-period variables. Most of
these stars lie close to the Galactic Plane, with a particular concentration in the ScoCen region
(towards the Bulge). Data are listed in Table A.4, and plotted in Figure A.2.
Semi-regular variables. — Sixteen stars are identified as semi-regular (AGB/RGB) variables.
As might be expected, the spatial and color-magnitude distributions are similar to those of the
Miras (Figure A.2, Table A.5), with a strong concentration towards the Plane and the Bulge.
Other. — A further eighteen stars are identified as late-type stars based on cross-referencing
against SIMBAD. Those stars are listed in Table A.6. Most are late-type giants. In particular, StM 218 is from Stephenson’s survey of high-latitude red giants (Stephenson 1986),
with additional spectroscopy by Sharples, Whitelock, & Feast (1995); BR B0954-0947 is from
the APM QSO survey (Kirkpatrick, Henry, & Irwin 1997); and the DENIS source, from PhanBao et al. (2001) is a known red-giant variable. Of the remaining stars, WOH S 11 is listed as
type M by SIMBAD, but with no additional information, and TX CVn is a symbiotic binary.
Unmatched sources. — Two hundred two sources have no obvious counterpart in the SIMBAD
database. 2MASS data for those sources are listed in Table A.7, and the spatial and colormagnitude distribution plotted in Figure A.3. As discussed in the text, all of these sources have
optical counterparts, indicating low proper motions, and most have optical/near-infrared colors
which are inconsistent with late-type dwarfs. Given those characteristics, plus the distribution
in Galactic coordinates, all are likely to be pre-main-sequence stars or AGB stars.
A.3
A.3.1
Discussion
The Reddest Candidates
The overwhelming majority of the sources listed in Tables A.1 to A.7 are clearly red giants.
Nonetheless, eight sources in Table A.2 and twenty-three sources in Table A.7 have (H−KS ) > 0.45—
148
colors potentially consistent with L dwarfs. We discuss these sources in detail below:
• The stellar candidates: all have excellent positional agreement between 2MASS and SIMBAD
(ICRS) co-ordinates. Three (V355 Gem, CD CVn and BD-08 2741) are known giant stars,
and it is extremely likely that the remaining eight are also red giants.
2MASSI J0609248+773327: BD+77 225, spectral type K0: V = 9.49, so (V −KS ) = 3.47,
consistent with MV ∼ 9.0 and spectral type M0 if it were a dwarf. Those parameters
would place it within 10 parsecs of the Sun. However, the low proper motion ((µα , µδ ) =
−12, −0.2 mas yr−1 ) and the inconsistency between the (V − KS ) color and the observed
spectral type indicates that this star is a giant.
2MASSI J0700365+260818: GSC 01899-00620, and also identified as V355 Gem and IRAS
06575+2612. This is clearly an evolved star.
2MASSI J1300025+472632: CD CVn, listed as V = 9.39, (B − V ) = 1.19, spectral type
K0 III and π = 3.31±1.21 by SIMBAD. This is a red giant variable, with (V −KS ) = 3.28.
2MASSI J1341018+563452: HD 238271, V = 9.55, (B − V ) = 1.51, spectral type K5,
negligible proper motions (-7, 6.2 mas yr−1 ). The low proper motions confirm the star as
a red giant, (V − KS ) = 3.64.
2MASSI J1724215+652915: BD+65 1182, V = 9.61, (B − V ) = 1.45, (V − KS ) = 3.45,
spectral type K2, negligible proper motions (-3, -6 mas yr−1 ). Again, the low motions,
measured colors and observed spectral type are most consistent with a giant.
2MASSI J1726192+601748: BD+60 1757, V = 9.94, (B − V ) = 1.66, (V − KS ) = 4.15,
spectral type K2, negligible motions (-12, 9 mas yr−1 ). As with 2M 1724, the low motions,
measured colors and observed spectral type are most consistent with a giant.
2MASSI J1816212+202817: HD 348183, V = 9.06, (B − V ) = 1.52, negligible motions
(-7, -6 mas yr−1 ), spectral type K7. (V − KS ) = 3.92, and another red giant.
2MASSI J2015149−153626: GSC 06315-00584, also identified as NSV 12940, a red giant
variable.
• The 34 sources with no SIMBAD identification: as noted above, all of these sources have optical
counterparts. Genuine ultracool dwarfs are expected to have (B − R) > 4 and (R − KS ) > 7
for (H − KS ) > 0.45 (spectral type later than M8). The corresponding distances (for ultracool
dwarfs) are less than 5 parsecs, so the absence of any measured proper motion (µ < 0.1 arcsec
yr−1 ) would require transverse velocities of less than 2.5 kms−2 .
2MASSI J0547281−214723: (B − R)U SN O = 3.0, (R − KS ) = 4.2. Spectroscopy with the
CTIO 1.5 m confirms this as a carbon star.
149
2MASSI J0613450+522540: (B − R)U SN O = 2.1, (R − KS ) = 6.5, with no evidence for
motion between POSS I and either POSS II or 2MASS. The source appears significantly
brighter on the POSS II F plate than on the POSS I E, suggesting variability, and identify
this star as a probable AGB variable.
2MASSI J0620521−164541: (B − R)U SN O = 1.2, (R − KS ) = 7.2, with no evidence for
significant proper motion. CTIO spectroscopy confirms this as an M giant.
2MASSI J0641403−282102: (B − R)U SN O = 0.8, (R − KS ) = 5.8, with no evidence for
significant proper motion. CTIO spectroscopy confirms this as an M giant.
2MASSI J0650548−372922: (B − R)U SN O = 4.1, (R − KS ) = 7.9, with no evidence for
significant proper motion. CTIO spectroscopy confirms this as an M giant.
2MASSI J0652228+452045: (B − R)U SN O = 1.6, (R − KS ) = 5.2, and no evidence for
motion between POSS I and either POSS II or 2MASS. This is likely to be a red giant.
2MASSI J0657520+662111: (B − R)U SN O = 1.3, (R − KS ) = 5.3, and no evidence for
motion between POSS I and either POSS II or 2MASS. Given the Galactic latitude,
b = +25◦ , the colors are most consistent with a reddened background star.
2MASSI J0658118+263535: (B − R)U SN O = 5.0, (R − KS ) = 4.7, with no evidence for
significant proper motion. CTIO spectroscopy confirms this as an M giant.
2MASSI J0701322−381421: (B − R)U SN O = 3.2, (R − KS ) = 5.4, with no evidence for
significant proper motion. CTIO spectroscopy confirms this as an M giant.
2MASSI J0703356−404748: (B − R)U SN O = 5.9, (R − KS ) = 5.5, b = −15◦ . Highly likely
to be a reddened source.
2MASSI J0710483+305546: (B − R)U SN O = 4.7, (R − KS ) = 4.4. No motion evident,
and clearly fainter on POSS II than POSS I. Likely to be a red giant variable.
2MASSI J0710574+475818: (B − R)U SN O = 3.8, (R − KS ) = 5.0, and no evidence for
significant proper motion. Likely to be a red giant or reddened background star.
2MASSI J0721404+194350: (B − R)U SN O = 1.9, (R − KS ) = 4.9. CTIO spectroscopy
identifies this as an M giant.
2MASSI J0813343−051321: (B − R)U SN O = 4.0, (R − KS ) = 4.9. CTIO spectroscopy
identifies this as a carbon star.
2MASSI J0829151+182307: (B −R)U SN O = 4.6, (R−KS ) = 4.4. No evidence for motion;
colors strongly suggest highly reddened object.
2MASSI J1010015−023743: (B − R)U SN O = 3.1, (R − KS ) = 4.4. CTIO spectroscopy
identifies this high-latitude (b = 41◦ ) candidate as an M giant.
2MASSI J1158169−253753: (B − R)U SN O = 1.6, (R − KS ) = 4.3. CTIO spectroscopy
identifies this as another high-latitude (b = 36◦ ) M giant.
150
2MASSI J1502099+593121: (B − R)U SN O = 2.2, (R − KS ) = 6.4, but relatively faint on
the POSS II IVN plate (I ∼ 15) and barely visible on the IIIaJ plate (B ∼ 21). This is
likely to be a high latitude red giant variable.
2MASSI J1502582−355111: (B − R)U SN O = 0.8, (R − KS ) = 6.8. Significantly brighter
on the UKST IIIaF plate than on the POSS I 103aE plate, and no evidence for motion.
This is likely to be a red giant variable.
2MASSI J1930155−232048: (B − R)U SN O = 0.9, (R − KS ) = 8.2, no evidence for motion
and near the Lupus dark cloud. Likely to be a pre-main sequence star or dusty giant.
2MASSI J1942441−295436: (B − R)U SN O = 4.6, (R − KS ) = 4.9, and no evidence for
motion. Likely to be a dusty giant.
2MASSI J2025464−163148: (B − R)U SN O = 0.2, (R − KS ) = 6.3, and no evidence for
motion POSS I/POSS II/2MASS. Brighter on second epoch UKST IIIaF than IVN,
suggesting identification as a red giant variable.
2MASSI J2044540−074359: (B − R)U SN O = 2.1, (R − KS ) = 6.8, and no evidence for
motion. Significantly fainter on UKST IIIaF plate, strongly suggesting variability and
identification as a red giant.
A.3.2
Cross-checks Against Existing Catalogs
As an additional test, all of the bright ultracool candidates were cross-referenced against the
third Catalog of Nearby Stars (Gliese & Jahreiß 1991, pCNS3) and against Luyten’s NLTT proper
motion catalog Luyten (1979). The two catalogs were cross-referenced using a search based on
position with a search radius of 18000 . There are only twelve matches, including G180-11, G139-3,
BD-01 3925D, and EZ Aqr (Gl 866ABC) which are discussed in the main text. In each of the
remaining nine cases, it is clear that the 2MASS ultracool source is not the NLTT star.
A.4
Conclusions
The overwhelming majority of the 588 sources in the ultracool sample with J < 9 can be eliminated as candidate nearby dwarfs: 386 have previously-cataloged optical or infrared counterparts,
and the overwhelming majority of those are AGB stars. Of the remaining 202 sources, only twenty
three have colors sufficiently red to be candidate L dwarfs. All of the latter are visible on photographic plate material, and none have either measurable proper motions or optical/near-infrared
colors consistent with ultracool dwarfs. We conclude that four proper-motion objects, G 180-11,
G139-3, BD-01 3925D, and Gl 866 (Table 3.6) are the only genuine late-type dwarfs amongst the
ultracool candidates with J ≤ 9.
151
Figure A.1.— The (α, δ) and near-infrared J/(J − KS ) and (J − H)/(H − KS ) distributions for all
588 sources in the 2MASS bright ultracool sample. Zero hours of right ascension is on the left and
12 hours is in the center. The selection criteria are shown in the JHKS plane (dotted lines); also
shown are the fiducial giant sequence (dashed line), the dwarf sequence (solid line), and data for L
dwarfs from Kirkpatrick et al. (1999) (circles).
152
Figure A.2.— The (α, δ) and near-infrared J/(J − KS ) and (J − H)/(H − KS ) distributions for
2MASS ultracool sources matched against known carbon stars (crosses, Table A.3), Miras (squares,
Table A.4), semiregular variables (filled circles, Table A.5), and other late-type stars (triangles,
Table A.6). The lines of right ascension and the lines in the JHKS plane are the same as the
previous figure.
153
Figure A.3.— The (α, δ) and near-infrared J/(J − KS ) and (J − H)/(H − KS ) distributions for
ultracool sources with no counterpart listed by SIMBAD. The lines of right ascension and the lines
in the JHKS plane are the same as the previous figure.
154
Table A.1.
α (2000)
00
00
00
01
02
03
03
03
04
04
04
05
05
05
05
06
06
06
06
06
06
06
06
06
06
06
06
06
06
07
07
07
07
07
08
08
08
08
08
09
10
12
13
13
13
13
14
14
14
14
15
15
15
15
15
15
15
16
16
16
17
17
17
17
17
18
01
20
24
49
39
03
06
15
02
17
24
37
47
48
49
09
10
24
25
32
38
40
41
50
51
51
51
55
58
00
03
06
25
39
09
10
15
15
26
42
36
14
25
29
29
48
33
35
46
56
02
04
07
15
26
45
53
03
05
19
05
06
17
45
57
03
21.4
53.4
18.7
43.1
05.1
52.0
47.1
24.2
39.4
46.0
01.0
50.0
58.6
11.9
06.1
13.1
52.7
21.2
52.9
49.5
51.6
27.8
54.8
35.9
27.8
38.3
40.4
12.4
07.2
16.2
09.0
59.3
18.3
07.8
19.4
29.3
11.1
52.4
26.8
10.0
17.3
52.7
31.7
16.5
38.9
44.6
28.3
48.9
44.7
01.6
37.6
27.5
28.1
07.5
20.8
33.6
58.9
44.2
27.5
02.4
27.6
21.4
00.1
01.1
57.9
49.2
δ
51
50
34
38
31
45
28
40
21
18
−67
−15
−33
−32
−22
−27
−14
−18
−31
−63
−24
−27
51
−29
−36
−34
−59
−36
−38
−34
−36
−37
16
44
39
24
−04
−01
−03
−14
59
−10
−45
−33
−23
33
17
−23
−26
−26
−27
−30
−35
−19
−26
−20
−18
−13
−18
59
32
14
60
16
15
60
12
09
23
40
00
11
20
44
03
22
07
48
05
00
41
43
59
30
22
35
23
41
29
59
26
55
55
07
37
51
53
55
58
27
39
01
27
50
17
09
56
02
13
37
45
43
36
36
45
42
50
52
05
41
32
27
30
06
55
50
05
27
46
51
00
10
13
07
04
53
26
42
32
54
59
36
01
11
10
10
14
09
44
15
06
49
34
22
15
22
32
57
18
10
53
16
19
50
00
43
07
47
50
49
43
16
09
31
49
35
02
34
46
29
13
38
32
46
35
06
08
42
16
49
04
11
45
35
43
44
58
15
J < 9 Sources with IRAS Catalog Counterparts
J −H
H − KS
KS
J − KS
0.920
0.930
···
···
0.850
0.950
6.300
0.800
0.770
0.990
0.869
0.984
0.913
0.846
0.786
1.263
0.976
1.075
0.915
0.780
0.825
0.834
0.893
0.942
0.776
0.867
0.848
0.830
0.854
0.895
0.963
0.826
0.775
6.18:
0.773
0.906
1.083
0.937
0.847
0.819
6.00:
0.796
0.825
0.828
0.901
0.788
0.773
0.788
0.909
0.836
0.757
0.784
0.934
0.888
0.829
0.924
0.911
0.868
0.872
5.91:
0.790
0.859
0.749
0.870
0.934
0.794
0.700
0.590
···
···
0.450
0.530
···
0.320
0.510
0.520
0.463
0.690
0.637
0.453
0.412
0.931
0.482
0.584
0.571
0.604
0.415
0.373
0.521
0.606
0.620
0.514
0.437
0.432
0.558
0.538
0.615
0.474
0.345
···
0.350
0.466
0.687
0.470
0.481
0.477
···
0.333
0.460
0.451
0.518
0.448
0.534
0.619
0.469
0.525
0.505
0.566
0.572
0.450
0.637
0.741
0.582
0.484
0.577
···
0.313
0.471
0.300
0.446
0.523
0.434
6.910
5.480
4.830
4.960
6.070
5.360
4.890
5.350
5.120
5.840
5.460
4.890
6.167
5.202
6.490
6.308
6.470
6.535
6.756
5.607
6.410
5.836
4.949
6.088
6.007
5.271
6.264
6.098
6.307
5.120
6.009
6.359
5.371
5.069
5.237
4.990
6.641
5.094
5.838
5.075
4.714
5.527
6.380
6.524
6.287
5.482
6.841
5.145
5.988
5.902
5.329
6.968
5.516
5.511
6.934
5.465
5.300
5.026
5.183
4.822
5.347
6.364
5.412
5.276
5.608
6.435
1.620
1.520
1.060
1.100
1.300
1.480
1.410
1.120
1.280
1.510
1.332
1.674
1.550
1.299
1.198
2.194
1.458
1.659
1.486
1.384
1.240
1.207
1.414
1.548
1.396
1.381
1.285
1.262
1.412
1.433
1.578
1.300
1.120
1.110
1.123
1.372
1.770
1.407
1.328
1.296
1.285
1.129
1.285
1.279
1.419
1.236
1.307
1.407
1.378
1.361
1.262
1.350
1.506
1.338
1.466
1.665
1.493
1.352
1.449
1.089
1.103
1.330
1.049
1.316
1.457
1.228
155
ID
IRAS 23587+5055
IRAS 00182+4952
IRAS 00216+3406, M0
IRAS 01467+3826
IRAS 02361+3047
IRAS 03005+4459
IRAS 03037+2808
IRAS 03121+4033
IRAS 03597+2055
IRAS 04148+1815
IRAS 04238-6713
IRAS 05355-1549
IRAS 05461-3306
IRAS 05463-3201
IRAS 05469-2242
IRAS 06072-2742
IRAS 06086-1459
IRAS 06222-1828
IRAS 06329-3120
IRAS 06325-6333
IRAS 06367-2420
IRAS 06384-2738
IRAS 06379+5132
IRAS 06486-2955
IRAS 06497-3622
IRAS 06498-3452
IRAS 06509-5951
IRAS 06534-3603
IRAS 06564-3833
IRAS 06584-3447
IRAS 07013-3648
IRAS 07052-3751
IRAS 07224+1703
IRAS 07355+4434
IRAS 08059+3947
IRAS 08074+2410
IRAS 08126-0418
IRAS 08133-0141
IRAS 08239-0307
IRAS 09397-1355
IRAS 10330+6011
IRAS 12123-0946
IRAS 13225-4458
IRAS 13264-3321
IRAS 13269-2329
IRAS 13465+3358
IRAS 14311+1749,CO Boo
IRAS 14329-2323
IRAS 14438-2632
IRAS 14530-2630
IRAS 14596-2738
IRAS 15014-3041
IRAS 15043-3454
IRAS 15121-1929
IRAS 15233-2621
IRAS 15426-2018
IRAS 15511-1821
IRAS 16009-1258
IRAS 16025-1846
IRAS 16182+5957
IRAS 17035+3209
IRAS 17041+1431
IRAS 17163+6049
IRAS 17428+1652
IRAS 17556+1501
IRAS 18031+6009
Table A.1 (cont’d)
α (2000)
18
18
18
18
18
18
18
18
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
20
20
20
20
20
20
20
20
20
20
21
21
21
21
21
21
21
21
21
22
22
22
22
22
23
23
23
09
17
19
23
23
25
32
56
21
22
34
36
37
39
39
42
42
42
43
44
49
58
58
59
07
09
13
18
21
23
27
29
30
34
10
12
12
12
14
26
35
35
59
34
35
56
58
59
07
14
19
30.7
24.5
30.4
10.3
18.0
29.6
53.8
49.2
16.8
05.0
33.4
44.5
37.7
06.4
27.7
08.9
29.4
34.7
04.8
59.5
23.1
28.5
43.2
58.0
02.2
17.8
15.9
44.6
09.3
53.1
18.5
23.8
03.3
13.3
17.1
09.9
16.7
31.7
45.4
56.9
26.6
26.6
04.0
23.9
28.4
00.7
35.1
56.8
48.1
06.3
31.3
δ
31
42
35
25
24
31
43
47
−22
−38
−33
−15
−14
−16
−13
−28
−36
−13
−21
−31
−17
−02
−36
−22
−15
−28
−19
−20
−19
−12
−01
00
−28
00
18
18
22
21
−27
13
17
16
−25
44
40
43
30
35
29
31
46
12
36
00
41
43
33
01
57
39
50
48
19
36
16
00
46
04
55
00
14
58
27
51
58
23
39
53
54
23
49
59
49
48
50
34
49
17
29
58
16
24
26
32
28
10
23
24
09
17
04
52
30
16
21
07
16
05
03
10
57
38
18
25
51
58
01
11
35
58
53
14
21
28
44
14
25
30
55
45
42
17
20
02
49
24
40
02
55
59
41
54
06
01
44
07
25
39
38
48
55
42
25
J −H
H − KS
KS
J − KS
0.945
0.766
0.841
0.831
0.812
0.802
0.847
1.107
0.864
0.847
0.943
1.029
1.089
0.867
0.927
0.857
1.020
0.941
0.889
1.003
0.883
0.908
0.943
0.907
0.924
0.822
0.952
0.858
0.944
0.758
0.927
1.006
0.942
0.887
5.950
0.820
0.960
5.820
0.818
0.780
0.790
0.800
0.913
5.750
6.210
0.850
0.710
0.830
0.910
0.840
1.120
0.480
0.470
0.423
0.533
0.598
0.573
0.624
0.674
0.450
0.628
0.482
0.523
0.702
0.643
0.517
0.453
0.489
0.536
0.457
0.482
0.498
0.514
0.505
0.556
0.532
0.526
0.511
0.592
0.700
0.495
0.558
0.492
0.498
0.468
···
0.500
0.660
···
0.663
0.470
0.580
0.420
0.487
···
···
0.550
0.430
0.460
0.490
0.370
0.570
7.145
6.516
5.409
6.566
7.160
6.892
6.441
6.225
5.571
6.351
5.582
5.580
6.162
5.609
6.502
7.397
4.927
5.242
4.986
5.427
5.457
5.967
5.265
5.833
4.958
4.985
5.281
5.624
5.792
6.733
5.623
5.105
5.691
5.432
4.530
5.380
7.290
4.470
6.824
5.390
7.260
5.630
4.860
···
4.880
5.790
6.990
5.980
5.700
5.560
6.160
1.425
1.236
1.264
1.364
1.410
1.375
1.471
1.781
1.314
1.475
1.425
1.552
1.791
1.510
1.444
1.310
1.509
1.477
1.346
1.485
1.381
1.422
1.448
1.463
1.456
1.348
1.463
1.450
1.644
1.253
1.485
1.498
1.440
1.355
1.420
1.320
1.620
1.350
1.481
1.250
1.370
1.220
1.400
···
1.330
1.400
1.140
1.290
1.400
1.210
1.690
156
ID
IRAS 180976+3111
IRAS 18158+4235
IRAS 18177+3459
IRAS 18211+2539
IRAS 18212+2441
IRAS 18236+3131
IRAS 18313+4258
IRAS 18554+4753
IRAS 19182-2245
IRAS 19186-3856
IRAS 19312-3354
IRAS 19339-1526
IRAS 19348-1443
IRAS 19362-1623
IRAS 19366-1306
IRAS 19390-2853
IRAS 19392-3611
IRAS 19397-1403
IRAS 19401-2108
IRAS 19417-3121
IRAS 19464-1805
IRAS 19558-0235
IRAS 19554-3659
IRAS 19570-2306
IRAS 20042-1532
IRAS 20062-2848
IRAS 20103-2003
IRAS 20158-2104
IRAS 20182-1933
IRAS 20211-1258
IRAS 20247-0209
IRAS 20268-0059
IRAS 20270-2858
IRAS 20316-0100
IRAS 21079+1822
IRAS 21098+1836
IRAS 21100+2205
IRAS 21102+2117, M7
IRAS 2117-2811
IRAS 21245+1303
IRAS 21330+1710
IRAS F21330+1612
IRAS 21562-2547
IRAS 22322+4412
IRAS 22332+3954
IRAS 22537+4307
IRAS 22562+3008
IRAS 22575+3453
IRAS 23053+2901
IRAS 23116+3048
IRAS 23171+4635, C*
Table A.2. J < 9 Sources with Stellar Counterparts
α (2000)
00
00
00
00
01
01
01
02
02
02
02
02
02
02
02
03
03
03
03
03
03
03
03
03
04
04
04
04
04
04
04
05
05
05
05
05
05
06
06
06
06
06
06
06
07
07
07
07
07
07
07
07
07
08
08
08
08
08
09
09
10
10
11
11
11
11
20
38
42
44
15
28
48
04
07
10
22
24
30
35
47
01
02
04
07
26
37
44
45
59
02
05
10
15
20
29
31
14
22
40
40
53
55
00
09
23
38
40
42
49
00
01
04
14
23
24
39
50
52
18
19
49
50
59
23
47
02
27
16
25
30
46
01.3
06.2
32.4
41.2
51.7
55.4
29.8
31.5
20.0
54.1
44.6
14.1
13.0
37.7
30.4
25.9
13.6
31.5
21.6
25.3
24.0
17.2
29.8
12.7
12.8
28.1
46.0
51.9
16.6
46.0
25.3
26.8
55.8
26.7
31.3
00.9
00.7
25.0
24.8
31.1
29.4
31.0
35.9
05.6
36.5
13.8
25.6
33.4
57.1
02.7
19.9
24.7
56.4
23.2
18.1
04.4
22.6
55.5
09.2
40.7
37.5
09.8
30.3
07.5
09.6
29.2
δ
51
37
33
47
−20
34
40
15
50
43
14
40
41
40
−21
−05
−23
−24
35
37
41
19
−11
15
21
18
−09
−66
18
−14
−25
−30
−17
−16
−17
−77
−23
−28
77
−17
−24
52
34
34
26
−37
−41
69
16
30
12
22
38
00
12
−18
−16
15
−10
−04
−11
23
−20
−29
17
−27
53
35
11
55
34
40
16
37
17
08
49
52
14
35
58
02
48
25
40
48
51
05
17
48
37
33
15
12
09
47
31
20
06
02
17
18
35
02
33
11
05
09
55
24
08
36
25
32
48
15
36
09
09
22
04
34
41
30
03
55
46
13
27
48
03
12
V
26
21
31
47
59
19
31
48
22
30
40
53
53
33
36
29
37
17
41
11
22
27
41
52
20
22
58
32
43
07
02
57
30
46
54
44
35
28
27
13
09
16
58
53
18
05
47
22
29
45
07
36
53
52
10
06
39
16
14
46
14
47
33
01
36
05
8.72
10.4
9.57
9.61
10.1
10.4
10.02
9.65
8.76
10.1
9.67
10.21
9.75
9.89
10.0
9.3
9.9
9.6
9.15
9.75
10.6
···
9.8
8.90
10.6
···
9.9
10.3
9.9
9.3
10.8
10.4
9.4
10.3
10.1
10.5
9.7
10.2
9.5
10.5
9.8
10.3
9.5
9.4
10.5
10.6
10.5
10.0
10.3
9.9
10.7
10.5
10.2
10.0
10.1
10.1
10.2
9.4
9.4
10.1
10.5
9.1
9.8
10.5
9.3
9.9
J −H
H − KS
KS
J − KS
5.630
0.720
0.740
0.670
0.689
0.690
0.690
5.470
5.760
0.810
0.800
0.750
0.740
0.790
0.765
0.756
0.703
0.754
6.140
0.720
0.620
0.780
0.784
5.550
0.730
0.770
0.800
0.774
···
0.786
0.726
0.776
0.796
0.744
0.748
0.766
0.827
0.751
0.703
0.783
0.768
0.682
0.597
5.88:
0.844
0.753
0.794
0.730
0.776
0.696
0.799
0.794
0.800
0.773
0.661
0.749
0.795
0.720
0.791
0.786
0.725
5.77:
0.688
0.740
5.64:
0.789
···
0.340
0.300
0.490
0.325
0.310
0.350
···
···
0.490
0.300
0.320
0.500
0.490
0.324
0.368
0.333
0.311
···
0.330
0.430
0.640
0.307
···
0.310
0.320
0.329
0.347
···
0.309
0.346
0.318
0.328
0.330
0.309
0.313
0.367
0.303
0.453
0.317
0.301
0.352
0.438
···
0.511
0.312
0.319
0.362
0.310
0.350
0.321
0.301
0.302
0.310
0.369
0.323
0.330
0.320
0.336
0.303
0.304
···
0.317
0.307
···
0.340
···
5.900
5.480
5.920
6.185
6.220
5.650
···
···
5.930
5.180
6.600
6.090
6.090
5.707
5.671
6.129
5.595
5.120
5.570
7.100
6.180
6.520
4.450
6.210
5.740
6.721
6.285
4.390
7.195
6.540
5.591
6.916
6.115
6.372
6.212
6.167
6.477
6.018
6.082
5.152
6.936
6.406
4.802
6.189
6.488
6.175
6.241
6.190
6.474
5.813
5.808
5.334
5.454
6.469
5.936
6.015
5.263
5.868
6.096
6.299
4.732
5.875
6.471
4.521
5.020
···
1.060
1.040
1.160
1.014
1.000
1.040
···
···
1.300
1.100
1.070
1.240
1.280
1.089
1.124
1.036
1.065
1.020
1.050
1.050
1.420
1.091
1.100
1.040
1.090
1.129
1.121
···
1.095
1.072
1.094
1.124
1.074
1.057
1.079
1.194
1.054
1.156
1.100
1.069
1.034
1.035
1.078
1.355
1.065
1.113
1.092
1.086
1.046
1.120
1.095
1.102
1.083
1.030
1.072
1.125
1.040
1.127
1.089
1.029
1.035
1.005
1.047
1.123
1.129
157
ID
HD 232159, K5
GSC 02784-01363, M
BD+32 116, K5
BD+47 182, K5
BD-21 199
GSC 02300-01336
GSC 02819-01779
BD+14 334, M2
BD+49 555
GSC 02842-01596
BD+14 386, K2
GSC 02835-00621
BD+40 535, K2
GSC 02836-00893
BD-22 481 K5
BD-05 562
CD-24 1384 K5
CD-24 1405 K5
HD 278277, K2
HD 275416, M0
GSC 02870-10994
GSC 01256-00228
BD-11 729
HD 285324, M0
GSC 01262-00909
HD 285353, K5
BD-09 838
CPD-66 267B
HD 285651, M0
PPM 710748
GSC 06467-02288
CD-30 2265
PPM 711510
GSC 05917-01476
BD-17 1208
PPM 784266
CD-23 3232
CD-28 2635
BD+77 225 K0
BD-17 141
CD-23 4148
GSC 03389-00656
GSC 02443-00593
HD 264056 M2
GSC 01899-00620
GSC 07629-00161
GSC 07367-00412
BD+69 412 B5!
GSC 01347-00105
GSC 02452-01602
GSC 00773-00602
BD+22 1785
GSC 02960-00950
GSC 04848-01624
GSC 00803-00179
BD-18 2490
BD-16 2604
HD 76958
PPM 716038
BD-04 2721
BD-11 2780
BD+23 2226 M0
BD-19 3217
CD-29 9084
BD+17 2364 M2
CD-26 8766
Table A.2 (cont’d)
α (2000)
11
12
12
13
13
13
13
13
14
14
14
14
15
15
15
15
15
15
15
15
15
15
16
17
17
17
17
17
17
17
17
17
18
18
18
18
18
18
18
18
18
18
18
19
19
20
20
20
20
20
20
20
20
20
20
21
21
21
21
21
21
21
21
21
22
22
58
15
26
00
18
28
41
47
28
44
44
57
11
14
14
21
27
31
37
45
47
49
51
21
22
24
25
26
31
36
39
57
04
05
06
07
09
15
16
16
16
19
32
48
59
06
12
14
15
16
18
19
27
28
33
01
03
06
13
35
37
42
51
59
01
12
53.1
49.7
32.0
02.5
18.1
01.0
01.8
40.5
46.3
37.9
52.6
59.8
48.5
23.0
43.0
53.1
37.6
01.8
14.5
01.7
34.1
19.0
51.0
00.1
17.9
21.5
20.7
19.2
07.0
09.2
26.8
10.6
45.7
52.9
09.7
49.9
42.5
48.0
08.3
21.2
34.2
42.9
47.7
12.5
17.0
51.7
35.0
04.8
14.9
23.7
47.3
52.1
31.9
53.9
16.7
55.9
41.5
47.5
24.2
26.7
39.3
06.9
51.6
11.1
16.7
51.4
δ
-8
28
65
47
−29
−07
56
−29
63
−23
−27
−22
−30
−35
−19
−13
−15
−24
−23
−23
−20
−16
47
41
36
65
65
60
49
52
14
26
18
20
76
35
51
32
21
20
23
27
76
−31
−27
−01
−02
−04
−15
−04
−17
−19
00
−04
−01
−30
17
17
−35
15
−23
−35
−10
−29
−01
−47
24
47
10
26
53
01
34
58
19
28
12
51
50
50
24
51
57
47
59
23
14
01
31
21
29
29
06
17
43
28
19
05
30
54
38
12
14
23
39
28
53
57
44
39
32
11
37
03
36
54
27
35
22
05
09
17
12
51
20
45
58
20
29
14
01
22
V
12
55
58
32
25
37
52
30
26
23
03
30
23
47
25
08
35
16
11
51
34
22
14
48
08
15
43
48
27
59
14
20
49
01
07
29
47
39
32
17
27
17
45
43
30
25
13
55
26
28
42
58
04
08
34
07
54
34
32
03
51
04
35
56
49
55
9.0
9.4
10.6
9.4
10.0
9.4
9.6
10.0
9.5
9.9
10.7
10.9
10.4
10.9
9.9
10.4
10.3
10.5
9.7
10.4
10.2
10.0
9.24
8.22
9.3
9.6
9.9
9.9
9.16
8.41
10.0
11.0
10.2
10.7
11.2
10.5
9.1
10.1
8.0
9.1
10.2
9.2
10.6
9.8
9.7
10.4
9.6
10.4
···
10.2
10.4
10.7
10.9
9.5
10.3
9.2
9.09
11.0
10.2
9.10
10.1
10.3
10.8
10.4
10.2
11.5
J −H
H − KS
KS
J − KS
0.769
5.56:
0.769
0.579
0.771
5.79:
0.726
0.785
0.600
0.774
0.772
0.779
0.738
0.787
0.741
0.798
0.789
0.719
0.797
0.748
0.787
0.772
···
···
5.85:
0.673
0.648
0.701
···
···
0.785
0.777
0.759
0.744
5.61:
0.759
5.52:
0.783
0.777
0.692
0.759
5.57:
0.779
0.765
0.792
0.753
0.776
0.798
0.819
0.787
0.784
0.779
0.781
0.798
0.755
0.723
0.780
0.750
0.646
0.630
0.820
0.727
0.765
0.739
0.800
0.780
0.324
···
0.325
0.557
0.302
···
0.450
0.302
0.412
0.310
0.330
0.332
0.320
0.310
0.302
0.313
0.309
0.313
0.338
0.304
0.311
0.309
···
···
···
0.566
0.449
0.672
···
···
0.306
0.311
0.319
0.302
···
0.349
···
0.300
0.333
0.628
0.301
···
0.320
0.306
0.352
0.318
0.318
0.319
0.481
0.309
0.309
0.365
0.368
0.313
0.310
0.300
0.360
0.310
0.380
0.520
0.363
0.300
0.316
0.307
0.310
0.339
5.253
4.437
6.540
6.112
5.771
···
5.911
6.006
6.323
5.363
6.710
6.516
7.063
6.760
5.793
5.941
5.158
6.836
6.082
6.099
6.911
5.685
4.700
4.360
4.792
6.157
6.429
5.788
4.260
4.200
5.224
6.981
6.105
6.609
4.520
6.789
4.441
5.540
5.160
5.135
5.344
4.481
5.605
5.797
6.054
6.650
5.754
5.634
6.820
5.449
5.833
6.551
5.515
5.540
6.114
5.135
4.970
6.640
6.374
5.760
5.981
6.735
6.755
6.754
5.609
6.258
1.093
1.121
1.094
1.136
1.073
···
1.176
1.087
1.012
1.084
1.102
1.111
1.058
1.097
1.043
1.111
1.098
1.032
1.135
1.052
1.098
1.081
···
···
1.061
1.239
1.097
1.373
···
···
1.091
1.088
1.078
1.046
1.086
1.108
1.086
1.083
1.110
1.320
1.060
1.094
1.099
1.071
1.144
1.071
1.094
1.117
1.300
1.096
1.093
1.144
1.149
1.111
1.065
1.023
1.140
1.060
1.026
1.150
1.183
1.027
1.081
1.046
1.110
1.119
158
ID
BD-07 3328
BD+29 2271
GSC 04161-00886
CD CVn K0 III
CD-29 10249
HD 117081 K5
HD 238271 K5
CD-29 10597
BD+63 1135 K2
CPD-22 5830
GSC 06754-00323
GSC 06748-00155
CD-30 12022
GSC 07324-00450
BD-18 4010
BD-13 4138
BD-15 4113
CD-24 12131
CD-23 12419
BD-22 4016 K5
PPM 732355
BD-15 4196
BD+47 2395, M0
BD+41 2820, K2
BD+36 2860 M2
BD+65 1182 K2
GSC 04206-00695
BD+60 1757 K2
BD+49 2652
HD 160270
GSC 01005-01782
GSC 02094-00083
GSC 01558-00135
GSC 01566-00162
BD+76 679 K5
GSC 02629-01650
HD 234573 M0
GSC 02626-00119
HD 341857 M0
HD 348183 K7
HD 341795 K5
HD 335891 M0
GSC 04570-00463
HD 186874 K1/K2III
PPM 735797
PPM 708186
BD-03 4816
BD-04 5062
GSC 06315-00584 var.
BD-05 5200
BD-17 5932
GSC 06336-01895
GSC 05163-00396
BD-04 5150
GSC 05176-00531
HD 200054 M0 III
HD 200564, K5
GSC 01653-01535
GSC 07480-00854
BD+15 4453, K0
CD-24 16749
CD-35 14918
BD-11 5686
GSC 06960-01221
GSC 05224-01090
CD-47 14098
Table A.2 (cont’d)
α (2000)
22
22
22
22
22
23
17
28
31
32
56
44
24.7
55.5
20.1
00.4
00.7
37.3
δ
−26
−21
19
24
41
47
20
36
26
52
37
24
V
42
19
16
05
03
27
10.8
9.8
10.5
10.1
9.46
10.36
J −H
H − KS
KS
J − KS
0.779
0.720
0.690
0.790
5.870
0.860
0.308
0.306
0.340
0.300
···
0.730
6.385
5.912
6.270
5.440
4.790
5.150
1.087
1.026
1.030
1.090
1.080
1.590
159
ID
GSC 06958-01172
HD 213032
GSC 01703-01220
GSC 02223-01112
BD+40 4943, M0
GSC 03642-00820
Table A.3.
α (2000)
01
02
03
03
03
06
06
07
07
07
11
12
20
58
13
08
12
27
14
15
00
06
54
45
24
03
51.1
29.9
48.7
46.9
31.3
35.9
27.2
01.7
07.7
13.2
01.4
32.7
34.2
δ
40
46
27
38
39
−15
47
35
40
72
64
−26
−25
37
20
54
47
04
01
54
05
12
13
47
14
27
20
20
59
50
50
09
25
56
01
39
37
08
15
Carbon stars
V
J −H
H − KS
KS
J − KS
12.1
13.5
···
···
···
13.0
···
···
···
13.8
···
13.6
12.0
1.180
0.860
1.030
0.970
1.110
1.034
1.232
1.126
1.076
1.050
0.777
0.815
0.783
0.740
0.480
0.530
0.580
0.530
0.565
0.838
0.723
0.523
0.520
0.489
0.369
0.319
6.630
6.570
6.190
6.070
7.020
6.382
5.883
6.628
7.088
5.985
6.034
7.219
7.261
1.920
1.340
1.560
1.550
1.640
1.599
2.070
1.849
1.599
1.570
1.266
1.184
1.102
160
ID
CGCS 298
CGCS 322
CGCS 444
V458 Per
FBS 0324+389
CGCS 1210
CGCS 1194
FBS 0656+351
FBS 0702+402
CGCS 1876
GSC 04156-00392
KV Hya
CD-25 14520
Table A.4. Miras and Long-period Variables
α (2000)
00
00
00
01
01
02
03
03
04
06
06
06
06
07
07
07
08
08
08
08
08
09
09
12
12
13
14
14
15
15
15
15
15
16
16
17
17
17
17
18
18
18
18
18
18
18
18
18
18
18
18
19
19
19
19
19
19
19
19
19
20
20
20
20
20
20
09
38
59
22
58
59
11
18
17
14
26
30
58
17
56
59
03
11
13
21
38
09
11
05
37
59
38
44
10
36
37
48
59
29
59
17
41
52
56
16
18
19
25
28
30
35
35
42
47
56
57
18
20
22
23
33
37
38
42
45
05
07
08
10
14
14
36.8
52.9
46.4
52.9
06.1
56.2
40.7
27.8
41.3
59.1
59.1
18.3
33.8
59.7
56.0
14.4
59.7
03.1
30.6
53.0
36.8
28.6
14.5
14.7
45.8
06.7
31.9
36.9
44.3
12.7
47.9
38.5
10.7
07.8
28.2
34.2
11.1
24.0
48.2
25.0
20.1
01.5
59.7
56.3
13.3
10.0
36.3
41.4
17.8
00.5
58.0
59.4
12.7
12.5
21.1
55.5
52.2
16.3
17.3
42.3
11.8
37.3
38.6
00.3
29.0
39.9
δ
37
45
27
25
38
42
41
42
−60
46
45
−60
31
23
31
20
73
23
13
−10
−16
−22
−09
12
65
−25
−29
−19
−20
−21
−16
−16
−14
34
12
16
12
34
25
46
31
22
31
32
37
42
39
35
53
39
43
−23
−40
−21
−23
−22
−14
−32
−37
−26
−02
−02
−04
−01
−21
−01
47
33
56
23
39
37
38
49
35
47
47
13
38
55
10
38
24
08
48
35
17
13
22
21
33
51
43
32
01
09
09
11
10
13
19
35
25
11
54
27
42
06
29
14
29
33
29
35
56
29
08
54
52
41
53
49
08
16
35
35
39
27
25
41
58
10
31
49
44
06
18
15
46
18
42
47
35
40
25
19
02
27
30
54
05
50
30
05
05
37
21
43
28
28
08
03
57
41
55
46
46
26
39
11
21
51
00
49
49
49
39
34
42
08
47
16
05
31
37
03
33
44
08
48
25
26
59
06
20
05
44
36
V
J −H
H − KS
KS
J − KS
12.4
···
11.4
···
···
···
···
···
11.5
11.5
11.5
10.0
10.0
10.0
11.0
11.0
10.5
9.0
11.0
10.4
11.0
13.3
11.0
8.4
8.4
10.0
9.8
10.0
10.2
10.0
10.3
14.0
11.0
11.5
10.0
13.0
12.0
12.0
12.0
11.0
10.0
14.0
···
10.0
10.0
13.5
···
12.6
12.0
14.0
13.0
12.7
12.2
13.2
13.2
11.0
12.0
11.0
12.5
11.5
13.0
13.0
12.5
12.0
11.0
12.0
1.010
0.780
0.770
···
0.800
0.850
0.840
0.820
0.793
0.873
0.793
0.800
0.834
0.805
0.784
0.770
0.801
5.49:
0.770
0.763
0.715
1.088
0.695
0.786
0.675
0.780
0.784
0.804
0.827
0.783
0.734
0.892
0.740
0.799
0.810
0.827
0.888
0.760
0.797
0.739
0.839
0.862
0.835
0.890
0.826
5.90:
0.838
0.789
0.802
1.043
0.798
0.737
0.837
0.840
0.829
0.839
0.831
0.822
0.859
0.838
0.969
0.907
0.931
0.873
0.825
0.895
0.530
0.490
0.430
···
0.360
0.630
0.450
0.360
0.474
0.467
0.450
0.438
0.445
0.444
0.476
0.446
0.403
···
0.327
0.502
0.444
0.682
0.516
0.435
0.335
0.490
0.421
0.358
0.493
0.372
0.522
0.745
0.560
0.312
0.497
0.470
0.476
0.490
0.327
0.383
0.514
0.444
0.419
0.542
0.375
···
0.442
0.470
0.464
0.674
0.467
0.547
0.534
0.457
0.476
0.484
0.553
0.619
0.455
0.502
0.523
0.542
0.519
0.588
0.479
0.521
5.430
7.710
5.980
4.580
6.830
5.720
5.210
6.230
5.621
4.932
5.505
5.952
6.295
5.324
5.922
5.019
5.739
···
6.511
6.274
6.739
4.980
5.605
5.357
5.825
7.007
5.372
5.681
5.880
6.398
7.199
6.065
7.650
7.840
4.862
5.522
6.025
6.166
6.776
6.666
5.113
7.590
7.339
5.692
6.916
4.577
6.256
7.003
6.501
4.828
4.591
6.931
5.601
6.546
6.395
5.827
6.287
6.876
6.919
5.906
4.841
7.080
4.693
6.539
5.272
5.670
1.540
1.270
1.200
1.400
1.160
1.480
1.290
1.180
1.267
1.340
1.243
1.238
1.279
1.249
1.260
1.216
1.204
···
1.097
1.265
1.159
1.770
1.211
1.221
1.010
1.270
1.205
1.162
1.320
1.155
1.256
1.637
1.300
1.111
1.307
1.297
1.364
1.250
1.124
1.122
1.353
1.306
1.254
1.432
1.201
1.328
1.280
1.259
1.266
1.717
1.265
1.284
1.371
1.297
1.305
1.323
1.384
1.441
1.314
1.340
1.492
1.449
1.450
1.461
1.304
1.416
161
ID
V414 And
V403 And
W Psc, M2e
TZ Psc
OY And
IV Per
GG Per
WW Per
ST Ret
ST Aur
BW AUr
RU Pic
FW Gem, M0
RV Gem
AO Gem
BP Gem, M8e
SW Cam, M5e
RR Cnc
SU Cnc
GG Hya
FR Hya
CC Pyx, M7
VV HYa
SU Vir, M3.5e
RV Dra, M1
FQ HYa
FU Hya
TW Lib
T Lib, M4
X Lib
W Lib
DM Lib
UV Lib
HT Her, ROTSEI
V440 Oph
V621 Her
V1068 Oph
V1015 Her
ER Her
HI Lyr
AO Lyr
V577 Her
ROTSEI
IX Lyr
KL Lyr
ROTSEI
ROTSEI
AX Lyr
BZ Dra
V356 Lyr
V357 Lyr
V1264 Sgr
V1158 Sgr
V2141 Sgr
V1269 Sgr
V1315 Sgr, M3e
EZ Sgr
DP Sgr
V2165 Sgr
V1167 Sgr
V901 Aql
V510 Aql
V580 Aql
V583 Aql.
W Cap, M5
V519 Aql
Table A.4 (cont’d)
α (2000)
20
20
20
21
21
21
21
21
22
22
22
22
22
23
23
32
40
06
09
26
49
49
03
05
12
43
53
17
47.5
28.2
37.0
42.6
46.7
46.4
19.0
31.4
33.9
59.5
50.9
17.4
30.7
59.6
δ
−03
−05
13
−01
13
16
20
22
14
35
−21
43
−32
46
51
17
27
20
44
34
37
41
00
30
09
40
55
45
40
12
00
05
17
53
46
45
31
05
51
28
40
12
V
J −H
H − KS
KS
J − KS
14.5
12.0
12.0
9.0
···
9.0
···
12.0
···
···
12.0
···
11.0
···
0.780
0.724
0.787
0.782
0.820
0.710
0.820
0.850
0.790
0.820
0.837
0.770
0.771
0.860
0.411
0.431
0.514
0.564
0.410
0.330
0.560
0.430
0.400
0.530
0.447
0.630
0.527
0.540
5.594
6.596
5.865
5.726
4.860
5.120
4.640
6.740
6.040
5.900
6.484
6.550
6.726
5.470
1.191
1.155
1.301
1.346
1.230
1.040
1.380
1.280
1.190
1.350
1.284
1.400
1.298
1.400
162
ID
SON 4473, M3e
V837 Aql
SS DEl
TX Aqr
HK Peg
TV Peg
EL Peg
CX Peg
DG Peg
XX Peg
AQ Aqr
ST Lac
SS PsA
AO And
Table A.5.
α (2000)
00
00
02
03
08
08
08
09
15
16
19
19
20
21
23
23
45
46
34
21
22
27
28
06
06
23
22
32
51
15
21
25
01.1
24.8
31.4
10.4
01.4
40.4
08.0
39.0
42.1
13.1
42.9
44.7
00.6
02.8
05.5
41.7
δ
48
47
40
−17
13
19
38
−19
−23
44
−32
−32
14
−09
45
45
41
41
04
13
37
15
20
18
25
08
08
14
31
46
24
42
02
33
06
56
05
43
22
44
38
28
03
14
15
37
30
04
Semi-regular Variables
V
J −H
H − KS
KS
J − KS
10.7
···
···
10.0
10.8
11.4
11.1
12.7
12.0
10.5
9.6
12.5
12.0
···
···
···
1.250
1.280
0.830
0.693
0.799
0.730
0.780
1.238
0.761
0.786
0.733
0.839
0.800
0.876
0.750
1.480
0.720
0.970
0.450
0.371
0.362
0.369
0.353
0.843
0.520
0.318
0.322
0.448
0.335
0.491
0.320
0.960
5.300
4.990
7.330
6.960
5.833
6.718
6.962
6.009
6.082
7.623
5.987
5.047
7.616
5.907
7.520
6.280
1.970
2.250
1.280
1.064
1.161
1.099
1.133
2.081
1.281
1.104
1.055
1.287
1.135
1.367
1.070
2.440
163
ID
V864 Cas
GSC 03266-01510
GU And
CO Eri
GT Cnc
GV Cnc
RX Lyn
V379 Hya
WZ Lib,
AY Her
AM Sgr
V347 Sgr
DZ Del
BY Aqr
V338 And
V339 And
Table A.6. Other Late-type Stars
α (2000)
04
08
09
09
12
15
15
17
17
18
19
19
19
19
19
20
20
20
27
53
31
56
44
01
12
25
25
21
36
44
51
52
56
01
10
24
42.7
26.7
01.7
32.9
42.0
12.8
15.2
13.0
42.3
09.5
20.0
48.9
51.7
52.4
56.8
57.7
21.2
32.9
δ
−73
−13
−23
−10
36
−25
−22
64
19
46
−18
−15
−05
−38
−11
−03
00
−29
11
31
09
01
45
39
59
26
33
08
29
11
48
10
48
42
13
44
08
16
00
17
50
24
07
12
26
57
18
20
16
03
05
39
26
02
V
J −H
H − KS
KS
J − KS
···
···
11.0
15.0
9.8
11.6
12.0
···
13.0
···
12.2
13.0
12.7
12.0
13.0
···
12.0
···
0.795
0.802
0.686
0.846
0.797
0.917
0.856
0.867
5.92:
0.680
0.821
0.901
0.965
0.777
0.936
0.975
0.913
0.733
0.316
0.374
0.319
0.660
0.420
0.493
0.438
0.471
···
0.475
0.657
0.577
0.652
0.341
0.507
0.552
0.740
0.329
7.742
6.566
7.526
5.755
6.198
7.126
5.690
6.603
4.630
6.137
6.524
6.737
5.328
6.593
5.788
6.599
7.006
7.391
1.111
1.176
1.005
1.506
1.217
1.410
1.294
1.338
1.299
1.155
1.478
1.478
1.617
1.118
1.443
1.527
1.653
1.062
164
ID
WOH S 11, M
V357 Hya, M-type variable
AT Hya Irr
BR B0954-0947, M8 III
TX CVn symbiotic
BV 1671, variable
StM 218, M6
FBS 1724+644, M
V400 Her, pulsating variable
Rotsei M-type variable
V3882 Sgr, variable
V362 Sgr, variable
EF Aql, variable
red giant
FI Sgr, variable
Son 8258, variable
EI Aql, variable
DENIS-P J202432.9-294402, BV 1735
Table A.7.
J < 9 Sources Without a Cataloged Counterpart
α (2000)
00
00
00
00
00
00
00
00
01
01
01
01
01
01
02
02
02
02
02
03
04
04
04
04
04
04
04
05
05
05
05
05
05
05
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
07
07
07
07
07
07
11
12
14
19
21
28
38
57
00
03
07
08
10
28
08
13
23
36
53
17
02
06
13
14
21
27
37
03
19
22
37
40
45
47
10
13
15
18
20
21
28
29
30
34
35
37
39
40
41
41
41
45
50
51
51
52
53
55
57
58
01
01
03
04
06
10
11.0
10.5
40.9
29.8
48.9
26.9
59.3
50.8
07.8
57.5
03.8
41.9
50.8
21.2
02.2
41.9
47.8
36.8
46.6
22.1
14.1
59.5
56.1
06.6
20.4
05.9
43.9
25.2
11.1
41.0
45.4
50.4
18.1
28.1
32.1
45.0
36.6
27.5
52.1
44.5
12.7
53.0
46.6
20.3
01.3
04.8
59.2
23.4
10.1
40.3
57.5
16.7
54.8
13.3
55.8
22.8
50.7
08.7
52.0
11.8
18.8
32.2
35.6
17.0
53.0
48.3
δ
48
46
40
48
44
31
−19
50
46
20
22
48
29
50
41
43
23
30
29
24
20
20
19
19
−02
00
−25
73
−25
−12
−23
−21
−19
−21
−24
52
−18
−35
−16
−18
−21
−21
−76
−39
−21
−40
−34
−41
−35
−28
−40
−30
−37
−37
−41
45
−37
−37
66
26
38
−38
−40
24
40
30
58
53
34
38
52
24
27
50
11
11
16
20
17
14
13
25
03
16
32
07
57
23
23
45
50
22
20
49
36
08
54
57
57
47
49
25
46
25
45
54
24
22
43
35
40
56
24
28
59
21
29
08
29
56
04
20
41
57
21
35
30
14
47
57
47
55
43
30
52
27
18
11
42
07
36
45
06
03
27
51
08
32
41
20
48
02
40
22
54
41
02
53
34
21
46
29
39
04
07
23
27
40
52
27
41
21
15
59
09
18
10
35
16
04
43
02
44
35
22
49
40
45
56
18
11
35
01
21
48
47
29
46
J −H
H − KS
KS
J − KS
0.800
0.800
0.720
0.790
0.800
0.800
0.788
0.900
0.800
0.770
0.770
0.750
0.780
0.790
0.760
0.760
0.790
0.800
0.750
0.640
0.790
0.770
0.780
0.740
0.805
0.793
0.726
0.860
0.768
0.796
0.856
0.774
0.789
1.014
0.729
0.868
0.766
0.798
0.896
0.798
0.807
0.788
0.635
0.789
0.795
0.785
0.764
0.730
0.745
0.834
0.798
0.735
0.950
0.817
0.780
0.874
0.828
0.761
0.861
1.187
0.838
0.877
0.846
0.777
0.793
1.022
0.320
0.310
0.460
0.310
0.420
0.310
0.355
0.450
0.310
0.300
0.300
0.310
0.330
0.310
0.300
0.300
0.310
0.300
0.300
0.450
0.340
0.300
0.300
0.370
0.422
0.300
0.330
0.438
0.312
0.322
0.428
0.311
0.363
0.550
0.339
0.508
0.331
0.310
0.460
0.316
0.406
0.329
0.366
0.432
0.342
0.314
0.313
0.333
0.326
0.452
0.329
0.315
0.511
0.365
0.395
0.661
0.370
0.301
0.556
0.672
0.432
0.468
0.454
0.308
0.317
0.546
5.750
6.700
6.350
7.800
7.490
6.630
6.733
7.370
7.790
6.990
7.260
6.980
7.820
6.180
7.630
6.620
7.070
7.040
7.290
6.550
7.060
7.280
7.050
7.250
6.960
6.602
7.306
6.498
6.800
7.636
7.493
6.793
6.058
7.111
6.935
7.295
7.260
6.202
6.661
7.615
6.966
6.403
7.915
6.941
6.374
7.683
7.511
7.103
6.434
6.761
6.393
6.646
7.118
6.580
7.665
6.147
6.693
6.925
6.103
6.713
7.362
6.847
7.059
6.255
5.454
6.588
1.120
1.110
1.180
1.100
1.220
1.110
1.143
1.350
1.110
1.070
1.070
1.060
1.110
1.100
1.060
1.060
1.100
1.100
1.050
1.090
1.130
1.070
1.080
1.110
1.227
1.093
1.056
1.298
1.080
1.118
1.284
1.085
1.152
1.564
1.068
1.376
1.097
1.108
1.356
1.114
1.213
1.117
1.001
1.221
1.137
1.099
1.077
1.063
1.071
1.286
1.127
1.050
1.461
1.182
1.175
1.535
1.198
1.062
1.417
1.859
1.270
1.345
1.300
1.085
1.110
1.568
165
RU SN O
10.9
10.8
10.2
11.8
9.1
9.9
10.9
13.9
12.1
11.7
10.6
10.8
11.6
9.5
11.1
11.6
11.0
10.4
10.7
10.6
11.2
11.2
10.9
11.7
12.9
9.5
10.7
10.9
11.3
10.2
13.3
9.9
9.8
11.3
10.4
13.8
10.9
9.9
14.7
11.1
11.7
13.0
···
14.2
10.0
11.7
11.1
10.5
10.3
12.6
10.8
11.6
15.0
10.9
11.5
11.3
11.2
10.1
11.4
11.4
12.8
12.2
12.6
10.4
10.3
11.0
Table A.7 (cont’d)
α (2000)
07
07
07
07
07
07
07
07
07
08
08
08
08
08
08
08
08
08
08
08
08
08
08
09
09
09
09
09
09
09
09
09
10
10
10
11
11
11
11
12
12
12
12
12
13
13
13
14
14
14
14
14
14
14
14
15
15
15
15
15
15
15
15
15
15
15
10
17
21
24
27
30
31
36
56
01
01
05
09
10
13
22
26
28
29
30
46
51
55
03
07
09
28
30
34
42
42
54
04
10
42
05
28
46
58
00
08
13
21
24
18
26
29
27
48
48
50
50
51
59
59
02
02
02
02
04
04
06
06
12
13
43
57.4
09.5
40.4
16.5
47.5
31.4
35.6
34.6
36.3
01.6
48.5
47.9
24.4
17.8
34.3
44.9
30.0
06.9
15.1
06.0
25.3
16.6
40.2
25.2
31.8
35.6
22.3
46.5
56.4
23.5
45.1
35.4
32.4
01.5
05.0
44.9
41.0
47.0
16.9
28.5
50.4
12.0
01.1
42.4
50.8
21.9
03.1
23.3
00.2
05.4
21.1
44.0
17.2
09.5
19.9
09.9
37.9
57.1
58.2
40.3
46.8
15.1
59.4
11.9
56.0
34.5
δ
47
27
19
14
18
22
41
15
18
00
50
52
−05
−04
−05
16
−04
−11
18
−12
−18
−07
−17
−21
−07
−10
−19
−19
−23
−09
−20
−19
−24
−02
−08
−21
−17
23
−25
64
−28
−26
−19
−27
−17
−19
−45
−35
−25
−23
−35
−19
−31
−27
−35
59
−35
−03
−35
−31
−32
−30
−18
−35
−30
−19
58
48
43
14
14
36
05
05
52
05
42
46
53
57
13
31
05
25
23
15
21
27
26
53
42
31
49
32
47
47
49
26
35
37
20
38
10
51
37
09
10
23
52
30
59
05
38
29
49
10
09
27
31
02
48
31
16
49
51
46
17
09
39
48
56
25
18
04
50
56
37
55
47
00
16
22
43
28
29
16
21
39
32
56
07
40
44
32
42
12
25
00
04
41
55
50
02
05
53
43
28
23
05
20
53
39
14
47
38
14
50
23
36
25
10
37
03
04
28
49
06
21
43
45
11
50
18
23
51
29
05
04
J −H
H − KS
KS
J − KS
1.056
0.782
0.900
0.791
0.838
0.834
0.760
0.787
0.791
0.797
0.784
0.838
0.787
0.731
1.230
0.763
0.805
0.736
1.033
0.819
0.729
0.811
0.794
0.774
0.805
0.750
0.742
0.798
0.779
0.799
0.742
0.781
0.779
0.824
0.784
0.699
0.801
0.760
0.774
0.798
0.766
0.703
0.794
0.781
0.766
0.744
0.793
0.799
0.776
0.792
0.794
0.758
0.800
0.721
0.776
0.914
0.788
0.796
0.849
0.788
0.782
0.739
0.797
0.695
0.884
0.746
0.530
0.304
0.464
0.370
0.373
0.433
0.301
0.319
0.367
0.324
0.300
0.375
0.313
0.367
0.714
0.327
0.366
0.311
0.604
0.365
0.354
0.367
0.308
0.404
0.369
0.313
0.312
0.341
0.300
0.320
0.305
0.338
0.356
0.465
0.312
0.314
0.366
0.301
0.497
0.353
0.373
0.300
0.307
0.326
0.333
0.309
0.338
0.329
0.342
0.305
0.312
0.300
0.306
0.301
0.321
0.476
0.321
0.311
0.515
0.304
0.332
0.344
0.307
0.357
0.445
0.415
7.354
7.261
6.497
6.934
5.616
5.699
6.303
7.015
7.181
7.251
6.565
7.142
5.444
7.770
6.910
6.716
5.833
7.567
7.090
7.495
6.125
6.578
6.985
6.239
5.114
7.613
7.113
6.789
6.462
6.354
7.478
6.284
6.413
7.008
6.971
6.672
6.831
5.792
7.098
6.129
7.423
6.907
6.872
6.695
7.545
6.914
6.678
6.431
7.869
6.383
7.728
7.080
7.263
7.484
6.207
7.316
7.881
7.211
7.299
6.455
6.311
7.509
6.470
7.408
7.024
6.413
1.586
1.086
1.364
1.161
1.211
1.267
1.061
1.106
1.158
1.121
1.084
1.213
1.100
1.098
1.944
1.090
1.171
1.047
1.637
1.184
1.083
1.178
1.102
1.178
1.174
1.063
1.054
1.139
1.079
1.119
1.047
1.119
1.135
1.289
1.096
1.013
1.167
1.061
1.271
1.151
1.139
1.003
1.101
1.107
1.099
1.053
1.131
1.128
1.118
1.097
1.106
1.058
1.106
1.022
1.097
1.390
1.109
1.107
1.364
1.092
1.114
1.083
1.104
1.052
1.329
1.161
166
RU SN O
12.3
11.6
11.4
10.6
12.0
12.4
9.9
10.8
11.5
11.4
10.9
12.1
9.0
11.9
11.8
11.5
10.7
11.5
11.5
11.7
9.5
12.0
10.4
9.9
9.7
11.1
10.8
11.4
9.7
10.4
10.9
11.1
11.1
11.4
10.6
10.58
12.3
10.7
11.4
11.8
11.1
10.7
10.4
11.0
11.5
15.1
11.1
10.1
12.2
10.1
11.5
10.6
11.3
10.8
10.5
13.7
14.0
11.0
14.1
10.1
10.3
11.1
9.8
10.7
···
11.0
Table A.7 (cont’d)
α (2000)
15
16
16
16
17
17
18
18
18
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
21
21
21
21
22
22
22
23
53
04
25
55
02
05
00
07
53
21
21
22
23
23
24
26
29
29
30
30
31
31
34
37
37
40
40
41
42
43
44
46
48
49
50
51
51
56
08
10
11
12
15
16
17
17
20
22
25
27
29
31
33
39
44
45
46
50
05
16
25
44
34
42
42
09
03.2
56.0
01.3
50.4
54.2
49.2
36.3
10.8
53.0
29.8
34.7
39.6
14.7
48.8
58.3
30.6
00.9
22.3
15.5
23.8
39.8
41.9
18.2
14.0
21.8
29.1
43.7
28.4
44.1
46.7
53.1
45.5
36.9
06.4
33.0
36.4
43.3
40.9
51.5
23.7
09.1
41.1
05.3
21.7
37.9
49.6
47.4
18.9
46.4
43.1
04.5
34.2
36.9
49.1
54.0
12.5
14.6
55.8
48.8
28.6
44.0
53.3
35.1
31.5
41.3
19.6
δ
−19
−19
49
31
33
35
13
53
−47
−23
−23
−32
−22
−41
−33
−19
−20
−22
−23
−23
−17
−20
−32
−24
−17
−35
−32
−20
−29
−18
−20
−28
−19
−20
−36
−24
−24
−24
−27
−19
−04
−23
−05
00
−27
−14
00
−27
−16
−39
−22
−02
−04
−23
−07
−04
−03
−21
13
20
16
−04
45
35
44
47
59
01
28
41
42
17
17
42
19
00
06
39
21
56
08
56
42
02
20
42
57
36
32
48
26
38
36
50
54
52
05
05
58
22
41
04
00
43
02
44
01
41
20
34
02
15
54
10
31
22
57
17
01
55
43
37
31
00
59
22
02
05
04
06
41
32
22
57
16
25
55
04
17
52
17
23
55
35
54
25
49
55
32
26
48
45
36
23
58
01
42
08
09
50
36
11
27
51
39
22
06
12
52
40
02
45
00
34
52
15
05
33
12
40
48
18
23
53
26
31
59
22
50
27
01
00
10
46
15
43
04
18
J −H
H − KS
KS
J − KS
0.772
0.760
0.715
0.785
0.786
0.793
0.793
0.775
0.770
0.756
0.796
0.792
0.764
0.810
0.783
0.796
0.684
0.793
0.769
0.758
0.742
0.758
0.818
0.784
0.795
0.763
0.862
0.790
0.883
0.789
0.747
0.760
0.725
0.772
0.701
0.772
0.804
0.749
0.760
0.744
0.821
0.773
0.775
0.705
0.786
0.696
0.763
0.791
0.826
0.772
0.758
0.776
0.876
0.785
0.836
0.782
0.795
0.761
0.790
0.780
0.740
0.759
0.850
0.740
0.830
0.790
0.347
0.347
0.303
0.317
0.346
0.356
0.316
0.335
0.333
0.335
0.307
0.306
0.317
0.362
0.312
0.325
0.361
0.312
0.494
0.305
0.400
0.348
0.418
0.308
0.360
0.333
0.437
0.361
0.458
0.314
0.350
0.331
0.332
0.333
0.308
0.364
0.355
0.301
0.303
0.334
0.419
0.300
0.321
0.304
0.321
0.307
0.304
0.316
0.497
0.304
0.319
0.344
0.440
0.357
0.487
0.305
0.308
0.343
0.360
0.310
0.360
0.343
0.510
0.320
0.370
0.450
6.777
7.248
6.868
6.870
6.840
6.611
6.434
7.071
6.294
6.202
6.717
6.492
7.061
7.301
7.018
7.176
7.447
6.767
7.730
6.948
7.431
7.391
7.094
7.279
7.242
6.954
7.692
6.524
7.315
6.811
7.555
6.938
6.927
7.321
7.017
6.767
7.796
7.127
7.506
7.029
7.432
7.483
6.146
6.761
6.780
7.770
7.436
7.528
6.492
6.557
6.563
6.069
6.270
6.317
7.418
7.248
7.365
6.279
7.410
6.870
7.060
6.867
7.460
7.820
5.860
6.800
1.119
1.107
1.018
1.102
1.132
1.149
1.109
1.110
1.103
1.091
1.103
1.098
1.081
1.172
1.095
1.121
1.045
1.105
1.263
1.063
1.142
1.106
1.236
1.092
1.155
1.096
1.299
1.151
1.341
1.103
1.097
1.091
1.057
1.105
1.009
1.136
1.159
1.050
1.063
1.078
1.240
1.073
1.096
1.009
1.107
1.003
1.067
1.107
1.323
1.076
1.077
1.120
1.316
1.142
1.323
1.087
1.103
1.104
1.150
1.090
1.100
1.102
1.360
1.060
1.200
1.240
167
RU SN O
10.7
11.0
10.8
11.0
10.3
11.1
10.3
10.9
10.4
9.7
10.6
10.0
11.0
12.2
10.7
11.0
10.8
10.6
15.9
10.4
11.2
11.6
11.8
11.4
11.4
10.6
14.8
11.4
12.2
10.4
11.2
10.3
10.8
11.0
11.2
10.9
11.9
10.4
11.1
11.0
12.5
11.0
10.9
10.7
11.1
11.4
11.3
11.7
11.0
10.4
9.5
10.5
11.8
10.3
14.2
10.9
11.4
9.9
11.9
10.5
11.9
10.2
15.5
12.1
11.6
10.9
Table A.7 (cont’d)
α (2000)
23
23
23
23
34
34
37
50
07.6
20.7
37.5
42.0
δ
46
42
41
23
20
23
53
19
02
08
37
41
J −H
H − KS
KS
J − KS
0.950
0.770
0.820
0.860
0.520
0.310
0.370
0.480
6.670
7.760
5.800
7.140
1.470
1.080
1.190
1.340
168
RU SN O
14.0
12.3
11.2
14.2
Bibliography
Allen, P. R., Trilling, D. E., Koerner, D. W., & Reid, I. N. 2003, ApJ, 595, 1222
Allen, P. R., Koerner, D. W., & Reid, I. N. 2004, in preparation
Basri, G. 2001, in ASP Conf. Ser. 223, 11th Cambridge Workshop on Cool Stars, Stellar Systems
and the Sun, ed. R. J. Garcia Lopez, R. Rebolo, & M. R. Zapaterio Osorio (San Francisco, ASP),
261
Basri, G. & Marcy, G. W. 1995, AJ, 109, 762
Becklin, E. E. & Zuckerman, B. 1988, Nature, 336, 656
Bergeron, P., Leggett, S. K., & Ruiz, M. T. 2001, ApJS, 133, 413
Bessell, M. S. 1991, AJ, 101, 662
Bessell, M. S. & Brett, J. M. 1988, PASP, 100, 1134
Boeshaar, P. C. 1976, Ph.D. thesis, Ohio State Univ.
Bouy, H., Brandner, W., Martı́n, E. L., Delfosse, X., Allard, F., & Basri, G. 2003, AJ, 126, 1526
Burgasser, A. J. 2004, ApJS, submitted
Burgasser, A. J. 2002, Ph.D. thesis, California Institute of Technology.
Burgasser, A. J., et al. 2002, ApJ, 564, 421
Burgasser, A. J., et al. 1999, ApJ, 522, L65
Burgasser, A. J., et al. 2000a, ApJ, 531, L57
Burgasser, A. J., Kirkpatrick, J. D., Liebert, J., & Burrows, A. 2003, ApJ, 594, 510
Burgasser, A. J., McElwain, M. W., Kirkpatrick, J. D., Cruz, K. L., Tinney, C. G., & Reid, I. N.
2004, AJ, in press (astro-ph/0402325)
Burgasser, A. J., et al. 2000b, AJ, 120, 1100
169
Burrows, A., Hubbard, W. B., Lunine, J. I., & Liebert, J. 2001, Reviews of Modern Physics, 73, 719
Burrows, A., Sudarsky, D., & Lunine, J. I. 2003, ApJ, 596, 587
Cannon, A. J. & Pickering, E. C. 1901, Ann. of Harvard Coll. Obs., 28, 131
Chabrier, G. 2001, ApJ, 554, 1274
Chabrier, G. 2002, ApJ, 567, 304
Close, L. M., Potter, D., Brandner, W., Lloyd-Hart, M., Liebert, J., Burrows, A., & Siegler, N.
2002a, ApJ, 566, 1095
Close, L. M., Siegler, N., Freed, M., & Biller, B. 2003, ApJ, 587, 407
Close, L. M., Siegler, N., Potter, D., Brandner, W., & Liebert, J. 2002b, ApJ, 567, L53
Cruz, K. L. & Reid, I. N. 2002, AJ, 123, 2828 (Paper III)
Cruz, K. L., Reid, I. N., Liebert, J., Kirkpatrick, J. D., & Lowrance, P. J. 2003, AJ, 126, 2421
(Paper V)
Cuby, J. G., Saracco, P., Moorwood, A. F. M., D’Odorico, S., Lidman, C., Comerón, F., & Spyromilio, J. 1999, A&A, 349, L41
Cushing, M. C., Vacca, W. D., & Rayner, J. T. 2004, PASP, 116, 362
Dahn, C. C., et al. 2002, AJ, 124, 1170
Dame, T. M., et al. 1987, ApJ, 322, 706
Delfosse, X., et al. 2001, A&A, 366, L13
Delfosse, X., Forveille, T., Udry, S., Beuzit, J.-L., Mayor, M., & Perrier, C. 1999, A&A, 350, L39
Delfosse, X., et al. 1997, A&A, 327, L25
Delfosse, X., Tinney, C. G., Forveille, T., Epchtein, N., Borsenberger, J., Fouqué, P., Kimeswenger,
S., & Tiphène, D. 1999, A&AS, 135, 41
Dutra, C. M. & Bica, E. 2002, A&A, 383, 631
Epchtein, N., et al. 1999, A&A, 349, 236 (DENIS)
EROS Collaboration et al. 1999, A&A, 351, L5
ESA 1997, The Hipparcos and Tycho Catalogues, ESA SP-1200 (Noordwijk: ESA)
Fan, X., et al. 2000, AJ, 119, 928
170
Forrest, W. J., Shure, M., & Skrutskie, M. F. 1988, ApJ, 330, L119
Freed, M., Close, L. M., & Siegler, N. 2003, ApJ, 584, 453
Garcia, B. 1989, Bulletin d’Information du Centre de Donnees Stellaires, 36, 27
Geballe, T. R., et al. 2002, ApJ, 564, 466
Gizis, J. E. 1997, AJ, 113, 806
Gizis, J. E. 2002, ApJ, 575, 484
Gizis, J. E., Monet, D. G., Reid, I. N., Kirkpatrick, J. D., & Burgasser, A. J. 2000, MNRAS, 311,
385
Gizis, J. E., Monet, D. G., Reid, I. N., Kirkpatrick, J. D., Liebert, J., & Williams, R. J. 2000, AJ,
120, 1085
Gizis, J. E. & Reid, I. N. 1997, PASP, 109, 849
Gizis, J. E., Reid, I. N., Knapp, G. R., Liebert, J., Kirkpatrick, J. D., Koerner, D. W., & Burgasser,
A. J. 2003, AJ, 125, 3302
Gliese & Jahreiß, 1991, Third Version of the Catalog of Nearby Stars (Heidelberg: Astron. RechenInst.) (CNS3)
Golimowski, D. A., et al. 2004, AJ, in press (astro-ph/0402475)
Hamuy, M., Suntzeff, N. B., Heathcote, S. R., Walker, A. R., Gigoux, P., & Phillips, M. M. 1994,
PASP, 106, 566
Harrington, R. S. & Dahn, C. C. 1980, AJ, 85, 454
Harrington, R. S., et al. 1985, AJ, 90, 123
Hawkins, M. R. S. & Bessell, M. S. 1988, MNRAS, 234, 177
Hawley, S. L., Gizis, J. E., & Reid, I. N. 1996, AJ, 112, 2799, VizieR On-line Data Catalog: III/198
(PMSU2)
Hawley, S. L., et al. 2002, AJ, 123, 3409
Hayashi, C. & Nakano, T. 1963, Prog. Theor. Phys., 30, 460
Hearnshaw, J. B. 1986, The Analysis of Starlight (Cambridge and New York: Cambridge Univ.
Press)
Hearty, T., Fernández, M., Alcalá, J. M., Covino, E., & Neuhäuser, R. 2000, A&A, 357, 681
171
Irwin, M., McMahon, R. G., & Reid, N. 1991, MNRAS, 252, 61
Johnson, H. L. & Morgan, W. W. 1953, ApJ, 117, 313
Jones, H. R. A., Longmore, A. J., Jameson, R. F., & Mountain, C. M. 1994, MNRAS, 267, 413
Joy, A. H. 1947, ApJ, 105, 96
Joy, A. H. & Abt, H. A. 1974, ApJS, 28, 1
Kendall, T. R., Delfosse, X., Martı́n, E. L., & Forveille, T. 2004, A&A, 416, L17
Kendall, T. R., Mauron, N., Azzopardi, M., & Gigoyan, K. 2003, A&A, 403, 929
Kenworthy, M., et al. 2001, ApJ, 554, L67
Kirkpatrick, J. D., Beichman, C. A., & Skrutskie, M. F. 1997, ApJ, 476, 311
Kirkpatrick, J. D., Henry, T. J., & Irwin, M. J. 1997, AJ, 113, 1421
Kirkpatrick, J. D., Henry, T. J., & Liebert, J. 1993, ApJ, 406, 701
Kirkpatrick, J. D., Henry, T. J., & McCarthy, D. W. 1991, ApJS, 77, 417
Kirkpatrick, J. D., Henry, T. J., & Simons, D. A. 1995, AJ, 109, 797
Kirkpatrick, J. D., Liebert, J., Cruz, K. L., Gizis, J. E., & Reid, I. N. 2001, PASP, 113, 814
Kirkpatrick, J. D., McGraw, J. T., Hess, T. R., Liebert, J., & McCarthy, D. W. 1994, ApJS, 94, 749
Kirkpatrick, J. D., et al. 1999, ApJ, 519, 802
Kirkpatrick, J. D., et al. 2000, AJ, 120, 447
Knapp, G. R., Leggett, S. K., Fan, X., Marley, M. S., Geballe, T. R., & Golimowski, D. A. 2004,
AJ, in press (astro-ph/0402451)
Koerner, D. W., Kirkpatrick, J. D., McElwain, M. W., & Bonaventura, N. R. 1999, ApJ, 526, L25
Kuiper, G. P. 1942, ApJ, 95, 201
Kumar, S. S. 1963, ApJ, 137, 1121
Lane, B. F., Zapatero Osorio, M. R., Britton, M. C., Martı́n, E. L., & Kulkarni, S. R. 2001, ApJ,
560, 390
Liebert, J., Kirkpatrick, J. D., Cruz, K. L., Reid, I. N., Burgasser, A., Tinney, C. G., & Gizis, J. E.
2003, AJ, 125, 343
Liebert, J., Boroson, T. A., & Giampapa, M. S. 1984, ApJ, 282, 758
172
Leggett, S. K., Allard, F., Dahn, C., Hauschildt, P. H., Kerr, T. H., & Rayner, J. 2000, ApJ, 535,
965
Leggett, S. K., Allard, F., Geballe, T. R., Hauschildt, P. H., & Schweitzer, A. 2001, ApJ, 548, 908
Leggett, S. K., et al. 2000, ApJ, 536, L35
Lépine, S., Rich, R. M., & Shara, M. M. 2003, AJ, 125, 1598
Lépine, S., Shara, M. M., & Rich, R. M. 2002, AJ, 124, 1190
Lodieu, N., Scholz, R.-D., & McCaughrean, M. J. 2002, A&A, 389, L20
Luyten, W. J. 1979, Catalog of Stars with Proper Motions exceeding 0.00 5 Annually (Minneapolis:
Univ. of Minnesota Press) (LHS)
Luyten, W. J. & Ebbighausen, E. G. 1936, AJ, 45, 188
Luyten, W. J. 1979, New Luyten Catalog of stars with proper motions larger than two tenths of an
arcsecond (Minneapolis: University of Minnesota), VizieR On-line Data Catalog: I/98A (NLTT)
Malmquist K. G. 1920, Lund Medd. Astron. Obs. Ser. II, 22, 1
Martı́n, E. L. & Ardila, D. R. 2001, AJ, 121, 2758
Martı́n, E. L., Brandner, W., Jewitt, D. C., Simon, T., Wainscoat, R., Connelley, M., Marley, M.,
& Gelino, C. 2001, PASP, 113, 529
Martı́n, E. L., Brandner, W., & Basri, G. 1999, Science, 283, 1718
Martı́n, E. L., Delfosse, X., Basri, G., Goldman, B., Forveille, T., & Zapatero Osorio, M. R. 1999,
AJ, 118, 2466
Maury, A. C. & Pickering, E. C. 1897, Ann. Harvard Coll. Obs., 28, 1
McCarthy, M. F., Bertiau, F. C., & Treanor, P. J. 1964, Ricerche Astronomiche, 6, 571
McCarthy, D. W., Probst, R. G., & Low, F. J. 1985, ApJ, 290, L9
McCarthy, Zuckerman & Becklin, AJ, 121, 3259
McCaughrean, M. J., Scholz, R.-D., & Lodieu, N. 2002, A&A, 390, L27
Monet, D. G., Dahn, C. C., Vrba, F. J., Harris, H. C., Pier, J. R., Luginbuhl, C. B., & Ables, H. D.
1992, AJ, 103, 638
Morgan, W. W. 1938, ApJ, 87, 589
173
Morgan, W. W., Keenan, P. C., & Kellman, E. 1943, An Atlas of Stellar Spectra, with an Outline
of Spectral Classification (Chicago: Univ. Chicago Press)
Morrison, J. E., McLean, B., & GSC-Catalog Construction Team, I. 2001, AAS/Division of Dynamical Astronomy Meeting, 32
Mould, J. R. 1976, ApJ, 207, 535
Nakajima, T., Oppenheimer, B. R., Kulkarni, S. R., Golimowski, D. A., Matthews, K., & Durrance,
S. T. 1995, Nature, 378, 463
Oke, J. B., et al. 1995, PASP, 107, 375
Oke, J. B., & Gunn, J. E. 1983, ApJ, 266, 713
Oppenheimer, B. R., Kulkarni, S. R., Matthews, K., & Nakajima, T. 1995, Science, 270, 1478
Phan-Bao, N., et al. 2001, A&A, 380, 590
Phan-Bao, N., et al. 2003, A&A, 401, 959
Pickering, E. C. 1890, Ann. Harvard Coll. Obs., 27, 1
Probst, R. G. & Liebert, J. 1983, ApJ, 274, 245
Rayner, J. T., Toomey, D. W., Onaka, P. M., Denault, A. J., Stahlberger, W. E., Vacca, W. D.,
Cushing, M. C., & Wang, S. 2003, PASP, 115, 362
Reid, N. 1987, MNRAS, 225, 873
Reid, I. N. 1993, MNRAS, 265, 785
Reid, I. N., Burgasser, A. J., Cruz, K. L., Kirkpatrick, J. D., & Gizis, J. E. 2001, AJ, 121, 1710
Reid, I. N. & Cruz, K. L. 2002, AJ, 123, 466
Reid, I. N. & Cruz, K. L. 2002, AJ, 123, 2806 (Paper I)
Reid, I. N., et al. 2004, AJ, in press (Paper VIII)
Reid, I. N., et al. 2003, AJ, 125, 354 (Paper IV)
Reid, I. N. & Gilmore, G. 1981, MNRAS, 196, 15
Reid, I. N. & Gizis, J. E. 1997, AJ, 113, 2246
Reid, I. N., Gizis, J. E., & Hawley, S. L. 2002, AJ, 124, 2721 (PMSU4)
Reid, I. N., Gizis, J. E., Kirkpatrick, J. D., & Koerner, D. W. 2001, AJ, 121, 489
174
Tinney, C. G., Reid, I. N., Gizis, J., & Mould, J. R. 1995, AJ, 110, 3014
Tsuji, T. 1964, Ann. Tokyo Astron. Obs., 9, 110
Tsvetanov, Z. I., et al. 2000, ApJ, 531, L61
Vacca, W. D., Cushing, M. C., & Rayner, J. T. 2003, PASP, 115, 389
van Altena, W. F., Lee, J. T., Hoffleit, E. D. 1995, General Catalog of Trigonometric Stellar Parallaxes (4th ed.; New Haven:Yale Univ. Obs.)
van Biesbroeck, G. 1944, AJ, 51, 61
van Biesbroeck, G. 1961, AJ, 66, 528
Vogel, H. C. 1874, Astron. Nachr., 84, 113
Vrba, F. J., et al. 2004, AJ, in press (astro-ph/0402272)
Webb, R. A., Zuckerman, B., Platais, I., Patience, J., White, R. J., Schwartz, M. J., & McCarthy,
C. 1999, ApJ, 512, L63
Weis, E. W. 1991, AJ, 101, 1882
Wilsing, J. & Scheiner, J. 1909, Publ. Astrophys. Obs. Potsdam, 19, 1
Wilson, J. 2002, Ph.D. thesis, Cornell Univ.
York, D. G., et al. 2000, AJ, 120, 1579 (SDSS)
176