Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Massive OB stars as seen by Gaia
Y.Frémat
Royal Observatory of Belgium
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
1 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
OB stars in the Gaia Universe Model
Robin et al., 2012, A&A, 543, 100
gaia.am.ub.es/GUMS-10/main.html
Luri et al., 2014, A&A, 566, A119
∼ 0.9 %
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
2 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
OB stars in the Gaia Universe Model
Robin et al., 2012, A&A, 543, 100
gaia.am.ub.es/GUMS-10/main.html
Luri et al., 2014, A&A, 566, A119
∼ 0.9 %
Y.Frémat, 22.06.2015 EWASS SP7
∼ 0.3 %
Massive OB stars as seen by Gaia
2 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
OB stars in the Gaia Universe Model
Robin et al., 2012, A&A, 543, 100
gaia.am.ub.es/GUMS-10/main.html
Luri et al., 2014, A&A, 566, A119
∼ 0.9 %
∼ 0.3 %
Represent 1 × 105 to 3 × 106 B stars, 1 × 103 to 1 × 104 O stars
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
2 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Image of the Week
NGC2516
http://www.cosmos.esa.int/web/gaia/iow_20140214
HD66259
HD65987
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
3 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Instruments on-board
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
4 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Astrometry
cosmos.esa.int/web/gaia/science-performance
• Average of 70 transits
• σπ ∼ 5 − 600 µas (B1V)
5 - 16 µas (V < 12)
26 µas (V = 15)
600 µas (V = 20)
• σµ α,δ ∼ 40 − 350 µas yr−1
Percentage (%)
Expected from Gaia
100
50
0
<1
<0.2
σπ /π
O Stars
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
<0.05
B Stars
5 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Astrometry
cosmos.esa.int/web/gaia/science-performance
Luri et al., 2014, A&A, 566, A119
• Average of 70 transits
• σπ ∼ 5 − 600 µas (B1V)
5 - 16 µas (V < 12)
26 µas (V = 15)
600 µas (V = 20)
• σµ α,δ ∼ 40 − 350 µas yr−1
Percentage (%)
Expected from Gaia
100
50
0
3.102 -3.103
104 -105
<1
<0.2
σπ /π
O Stars
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
<0.05
B Stars
5 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Astrometry
Gaia vs Hipparcos
cosmos.esa.int/web/gaia/science-performance
Luri et al., 2014, A&A, 566, A119
Expected from Gaia
73 O & 885 B stars with
σπ
π < 0.05
176 O & 8826 B stars with
σπ
π <1
• σµ α,δ ∼ 1 mas yr−1
251 open clusters in the
input catalogue
Y.Frémat, 22.06.2015 EWASS SP7
Percentage (%)
Hipparcos
100
50
0
3.102 -3.103
104 -105
<1
<0.2
σπ /π
O Stars
Massive OB stars as seen by Gaia
<0.05
B Stars
6 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Photometry
cosmos.esa.int/web/gaia/science-performance
Jordi et al., 2010, A&A, 523, A48
B1V Star, G=15-20
BP: 330 to 680 nm, σ ∼ 4
to 51 mmags
RP: 640 to 1000 nm, σ ∼ 4
to 110 mmags
G: σ ∼ 1 to 6 mmag
Average of 70 transits
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
7 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Photometry
G vs V
Jordi et al., 2010, A&A, 523, A48
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
8 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Photometry
Colour-Magnitude Diagrams
Johnson Cousins photometry from WEBDA
Conversion: Jordi et al., 2010, A&A, 523, A48
Parameters: Kharchenko et al., 2013, A&A, 558, 53
Isochrones: http://stev.oapd.inaf.it/cgi-bin/cmd, Girardi et al.
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
9 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Photometry
Dispersed Photometry
BP: 4 to 32 nm/pixel, 330 to 680
nm
RP: 7 to 15 nm/pixel, 640 to 1000
nm
SNR: from ∼ 250 (G= 6 to 12) to
< 20 (G=20), Bailer-Jones et al.
(2013, Fig.2)
OB AP relative errors (G = 10-15):
∆ Teff = 17 %, ∆ log g = 31 %,
∆ A0 = 12 %
Upper fig.: Bailer-Jones et al., 2013, A&A, 559, 74
Lower fig.: Liu et al., 2012, MNRAS, 426, 2463
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
10 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Spectroscopy
Coverage: 845 to 872 nm ;
3 CCDs
Resolution: 10600 to 11000
(D.Katz & O. Marchal)
Single and multiple transit
RV measurements
Average of 40 transits
Figure from: ESA/Gaia/DPAC/CU6/Observatoire de
Paris-Meudon/ Olivier Marchal, Carine Babusiaux & David Katz
Taken from: cosmos.esa.int/web/gaia/iow_20141124
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
11 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Spectroscopy
Expected SNR
SNR values from cosmos.esa.int/web/gaia/sn-rvs
GRVS to V conversion following Jordi et al., 2010, A&A, 523, A48
Teff calibration from Worthey & Lee, 2011ApJS, 193, 1
End-of-mission SNR:
. 350 – 450 (V=8),
. 20 – 30 (V=12)
Transit spectrum:
. ∼ 65 (V=8),
. ∼ 7 (V=11)
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
12 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Spectroscopy
Expected end-of-mission error on radial velocity
cosmos.esa.int/web/gaia/science-performance
fig. provided by R.Blomme
End-of-Mission, error on combined spectrum: 1 to 15 km/s (B stars, V < 11)
Expected minimum error on epoch RVs: Strongly depends on V.sin(i)
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
13 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Data Sampling
End-of-mission
Nb of transits in the direction of 371 open clusters taken from Dias et al. (2012)
Time-sampling
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
14 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Additional Products
Gaia photometric alerts:
http://gaia.ac.uk/selected-gaia-science-alerts.
Variability classification (CU7, L.Eyer et al.). (from release 4
on)
Multiple system classification (CU4, D.Pourbaix et al.). (from
release 3 on)
Stellar classification (CU8, C.Bailer-Jones et al.):
astrophysical parameters, identification of emission-line stars.
(from release 3 on)
Auxiliary data & software.
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
15 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Conclusion
Release Scenario
www.cosmos.esa.int/web/gaia/release
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
16 / 17
Introduction Astrometry Photometry Spectroscopy Sampling Other output Release scenario
Thank you
Y.Frémat, 22.06.2015 EWASS SP7
Massive OB stars as seen by Gaia
17 / 17