Science with ISO in the Virtual Observatory context
M.M. Sierra Gonzalez-Buitrago 1 ,2 , A.M.S. Richards 3 , P.Garcia-Lario1 , A.Salama 1 and the AVO team
1
2
3
ISO Da ta C entre, E uro p ea n Sp a ce A g ency, V illa fra nca d el C a stillo , P.O. B o x 5 0 7 2 7 , 2 8 0 8 0 Ma d rid , Sp a in.
Ministerio d e E d uca cio n y C iencia . A lca la 3 6 , 2 8 0 7 1 . Ma d rid . Sp a in.
ME R LIN/V LB I Na tio na l F a cility, University o f Ma nchester,J o d rell B a nk Ob serva to ry, Ma cclesfield , C heshire SK 1 1 9 DL, U.K.
Abstract
ISO data are available through the ISO Data Archive and also
through Virtual Observatory protocols. Here we present two
examples of the scientific usage of ISO data (images and spectra)
shown during the First Science Demonstration of the Astronom ical
Virtual Observatory that took place in January 2004. In particular,
we study two Star Form ing Regions (SFRs) to classify Young Stellar
Objects (YSOs) using the AVO demonstration package.
What is a VO?
Th e Virtu al Ob serv ato ry is an in tern atio n al
astro n o mical co mmu n ity -b ased in itiativ e. It aims to
allo w g lo b al electro n ic access to th e av ailab le
astro n o mical d ata arch iv es o f sp ace an d g ro u n d -b ased
o b serv ato ries an d sk y su rv ey d atab ases. It also aims to
en ab le d ata an aly sis tech n iq u es th ro u g h a
co o rd in atin g en tity th at p ro v id es co mmo n stan d ard s,
wid e-n etwo rk b an d wid th , an d state-o f-th e-art an aly sis
to o ls.
The AVO
Th e Astro p h y sical Virtu al Ob serv ato ry Pro ject (AVO)
is co n d u ctin g a research an d d emo n stratio n p ro g ramme
o n th e scien tific req u iremen ts an d tech n o lo g ies
n ecessary to b u ild a VO fo r Eu ro p ean astro n o my .
Th e AVO p ro to ty p e in clu d es man y fu n ctio n s av ailab le
in cu rren t h ig h lev el d ata v isu alizatio n p ack ag es, th e
main co mp o n en t o f th e so ftware is b ased o n th e C DS
Alad in v isu alisatio n in terface (B o n n arel et al. 2 0 0 0 ).
Characterising Young Stellar Objects with the VO
INTRODUCTION
VO SOLUTIONS
SIGNPOSTS OF THE YSO EVOLUTION
Th e mass d istrib u tio n , ev o lu tio n an d
en v iro n men t o f YSOs co n trib u tes to
u n d erstan d in g to p ics fro m th e su rv iv al
o f p ro to p lan etary d iscs to
en v iro n men ts ty p ical o f star b irth in th e
early u n iv erse. VOs can h elp to classify
YSOs mo re rap id ly an d accu rately . Star
fo rmatio n h as b een ex ten siv ely
mo d elled an d man y in d iv id u al o b jects
are well u n d ersto o d b u t th e p ro p erties
o f en tire YSO p o p u latio n s are o n ly
k n o wn in a statistical sen se; it is
ard u o u s to test mo d els ag ain st all th e
memb ers o f a star-fo rmin g reg io n . Th ere
is a d eg en eracy b etween d iag n o stics fo r
ag e, mass, metallicity an d en v iro n men t.
Sin g le wav eb an d d ata, e.g . IR co lo u rs,
can n o t reso lv e th is.
Mu lti-λ an d mu ltireso lu tio n stu d ies are v ital.
To o ls wh ich allo w to
access d ata an y wh ere in th e
wo rld , co mp are sp ectra an d
imag es an d man ip u late
th eir resu lts,all th ro u g h a
sin g le in terface, h av e b een
d ev elo p ed .W e sh o w h o w
ISO sp ectra an d imag es an d
XMM mu lti-en erg y imag es
are u sed to d isen tan g le th e
ag e-mass d eg en eracy an d
h o w milli-arcsec reso lu tio n
d ata can b e easily
id en tified fo r an o b ject o f
in terest in an arcmin field .
Th e y o u n g est stars h av e in trin sically co o ler IR co lo u rs
an d are also mo re o b scu red (red d en ed ). In fact th eir IR
emissio n may b e n o n -d etectab le o r mo re ev o lv ed
b ack g ro u n d stars can b e co n fu sin g ly red d en ed to o . So me
d iag n o stics o f ev o lu tio n ary stag e are as fo llo ws, tak in g
u p to a millio n y ears fo r lo w-mass YSO an d ten o r mo re
times faster fo r h ig h -mass o b jects.
•Cla ss 0 co n d en satio n s with in a h o t co re
•H 2 O an d C O lin es in su b -mm sp ectra (accretio n reg io n )
•Cla ss I accretio n d isc
•Lo w-mass YSO h av e rad io (micro )-jets, fain t h ard en ed Xray
•H 2 O lin es g o n e fro m su b -mm sp ectra
•Hig h -mass YSO can h av e b rig h ter IR , mo lecu lar o u tflo ws
•Cla ss II-III p re-main -seq u en ce stars with d iscs
•TTau ri (lo w-mass) sh o w so ft X-ray
•Hig h er mass HAeB e stars h av e fain t/n o X-ray
IR COL OUR SE L E CT ION OF CHAM AE L E ON YSOs
SPE CT RAL DAT A AND M E ASURE M E NT S IN NGC1 3 3 3
The plot sho ws IR co lo u rs mad e from th e 2 MASS catalogue, using theVOPlot plugin (VO India).
We create a data subset with Kmag erro rs <0 .2 and virtual columns containing the colours for
co mpariso n with e.g. Haisch et al. (2 0 0 0 , AJ, 120 1396). The highlighted objects (green) have
warmer co lo ur ch aracteristics o f mo re ev olv ed YSO. These are automatically picked out on the
2 MASS imag e on the rig h t. Th e 7 µm co ntours show some of the cooler sources. They were drawn
fro m an ISO image o b tain ed u sin g the Serv er selector for direct access to the ISO archive, which
h old s images an d spectra with metad ata wh ich conform to VO standards. The data tree and Info
Frame material are d erived o n th e fly fro m image or spectrum FITS headers.
Spectra are obtained with the Server selector to query the ISO archive and create a catalogue plane
displaying the positions of available spectra (blue). Clicking on an entry starts SpecView (developed at
STScI), to display the detector segments, transform units and apply flagging. IRAS4 shows the 1613 µm CO lines and the 179 µm H 2 O line, so it is a Class 0 YSO, the absence of the latter in SVS13
shows it is more evolved (Nisini et al., 2002, ApJ, 574, 246). SpecView can fit models and take
measurements; we log the 60, 100,170 µm fluxes. Pezzuto et al. (2002, MNRAS, 330, 1034)
showed that Classes 0–II YSO have distinctive colours at these wavelengths. Colours are made with
VOPlot from the log file measurements and confirm that IRAS4 is a Class 0 YSO and SVS13 is
ClassI-II.
Pro to co ls
Th e AVO p ro to ty p e allo ws d irect arch iv e access u sin g
n ewly d efin ed Simp le Imag e Access (SIA) an d Simp le
Sp ectral Access (SSA) p ro to co ls.
C o mp o n en ts
•AC E: Astro n o my C atalo g u e Ex tracto r (remo te o b ject
ex tractio n o f an imag e)
•SED: Sp ectral En erg y Distrib u tio n u tility
•SPEC VIEW : Sp ectral an aly sis to o l
•VOPLOT: 2 d imen sio n al p lo tter
•C ro ss-Match Serv ice: Po sitio n al cro ss-match facility
•C o lu mn man ip u latio n
Go als
•Fin d th e man y d ifferen t o b serv atio n s o f a g iv en o b ject
•Match th e d ifferen t o b serv atio n s
•C o mp are all th e in fo rmatio n ab o u t th e o b jects
av ailab le in ev ery catalo g u e
•C o mp are o b serv atio n s tak en at d ifferen t times
•C ircu mv en t in stru men tal limitatio n s
ISO in the AVO
Th e ISO Data Arch iv e (IDA) is b ased o n an o p en 3 -tier
arch itectu re: Data Pro d u cts, B u sin ess Lo g ic, User
In terface. Th is o p en arch itectu re, to g eth er with Jav a
an d XML tech n o lo g y h as h elp ed in mak in g th e IDA
in tero p erab le with o th er arch iv es an d ap p licatio n s.
Th is h as en su red its in teg ratio n in th e VO arch itectu re.
Th e in ter-o p erab le mech an isms are flex ib le, fast, d irect
an d secu re. Th is arch itectu re is esp ecially p o werfu l in
th e co n tex t o f th e wo rld wid e VO in itiativ es wh ere
arch iv es all h av e to in tero p erate in a man n er tran sp aren t
to th e en d u ser. Sin ce its first release in Decemb er
1 9 9 8 , th e IDA h as h ad in tero p erab ility with remo te
arch iv es an d ap p licatio n s (targ et n ame reso lu tio n v ia
NED an d SIMB AD, access to th e articles in ADS,
access to th e IR AS arch iv e in th e US, access fro m
Vizier, Heasarc, ADS, IR SA, etc.). IDA in tero p erab ility
in terfaces h av e b een p o rted to th e n ew VO stan d ard s
(SIA an d SSA, VOTab le, etc...) to mak e su re ISO d ata
can b e accessed fro m an y VO-en ab led arch iv e an d
ap p licatio n .
Th e AVO h as b een jo in tly
fu n d ed b y th e Eu ro p ean
C o mmissio n (u n d er FP5
Fifth Framewo rk
Pro g ramme) with six
Eu ro p ean o rg an isatio n s
p articip atin g in a th ree
y ear Ph ase-A wo rk
p ro g ramme.
LINKS:
www.eu ro -v o .o rg
www.iso .v ilsp a.esa.es
C ooler
M ore Obs cured
B RE AKING T HE AGE -M ASS DE GE NE RACY
M UL T I-RE SOL UT ION DAT A
The th ree central YSO in th e imag e ab o ve are all IR-bright and have cool JHK colours, they are
y ou ng an d /o r ob scu red . XMM d ata is ob tained using theServer selector. The Energy Band button
allo ws any o n e o f th e 5 su b -b an d s o r the full band to be listed. We load the 0.5-2.0, 2.0-4.5 and
4 .5 -7.5 k eV imag es an d with th eRGB image generator make a false colour image. If a source is
h id d en beh in d ab so rb in g g as on ly th e hardest X-rays can emerge, shown as blue. The lower
so urce in th e 7 µm co n to u rs is th e b rig htest in the 2MASS image but faintest in X-ray emission, and
n ot sig nifican tly o bscu red ; it is an HAeBe higher mass pre-main-sequence star. Both the upper
so urces are X-ray b rig h t, pro bab ly lo wer mass stars. The left hand object is heavily obscured,
p rob ab ly an emb ed d ed Class 0 YSO whilst the right-hand object is probably a TTauri star.
Radio interferometry provides high resolution as well as revealing sources in NGC1333 which
are obscured even in the FIR (Rodriguez et al., 1999, ApJS, 125, 427). An unpublished
MERLIN Deep Field covers the 10’ region at mas resolution.The IDHA hierarchical data model
provides organised access to these images. Clicking on a point in the low-resolution (POSSII)
image the corresponding high-resolution radio map is loaded. The viewer provides tools to
measure the angular size and flux density in the MERLIN image of MMS3. This gives a brightness
temperature ~8000 K consistent with thermal emission from a low-mass YSO microjet ~80 AU
long.