1. Corot Be stars group Be stars: The team:
Secondary targets candidates for the Core Programme
of asteroseismology
Targets for the Additional Programme
The team:
11 members (Belgium, Brazil, France and Spain)
People interested in joining our group are welcome!
Contact:
Website:
CorotWeek8 May 2005
Hubert/Neiner

2. Be stars as potential targets for the Additional Programme
Science goal for Be stars:
About 70 Be stars with 6<V<9.5 in the cones of COROT (seismology fields) including 15 new Be stars with V<8.0 (GAUDI) (Neiner, Hubert, Catala 2005)
Candidates for pulsations, rotation, activity, binarity studies (short runs)
Faint Be stars with 12<V<16.5 in the exoplanet fields
Candidates for asteroseismology (long runs)
CorotWeek8 May 2005
Hubert/Neiner

3.  Preparatory programs for bright Be stars
Photometric variability
Strömgren photometry (0.9m-T in Granada) : periodicity in early Be stars candidates (Gutierrez-Soto et al. 2003) and even multiperiodicity for NW Ser and V1446 Aql (Fabregat, this COROTWeek)
Spectroscopic variability (LNA + OHP+ multisite)
Determination of fundamental parameters taking into account fast rotation and veiling (Frémat, et al. 2005)
Search for magnetic fields (EsPaDoNS, CFHT)
CorotWeek8 May 2005
Hubert/Neiner

4. Determination of stellar parameters
Data : GAUDI + OHP + LNA + FEROS
Rapid rotation  stellar flattening + gravitational darkening effects
FASTROT (Frémat & Zorec)
- assumes: Rigid rotator (Roche model)  log g
Von Zeipel law  Teff
Local model atmospheres
- LTE temperature and pressure distribution
(ATLAS9, Kurucz)
- NLTE level populations (TLUSTY, Hubeny & Lanz)
CS envelope  veiling effect
CorotWeek8 May 2005
Hubert/Neiner

5. From modeling of different spectral domains  Teff, logg, Vsin i and i for a given /c
Without correction for rotational effects:
Teff = 25450°  1000°K,
log g = 3.87  0.10
V sini = 310  30 km/s
With corrections for /c= 0.9 (value
adopted from Frémat, Zorec et al., in press):
Teff = 26000°  1000°K,
log g = 4.10  0.10
V sini = 325  30 km/s, i ~ 60°
: observed spectrum
: fitted spectrum
CorotWeek8 May 2005
Hubert/Neiner

6. Location of Be stars in the HR diagram
Without correction for rotational effects
With corrections for
/c=0.9
CorotWeek8 May 2005

7. Different Be star spectral distributions between the Galactic Centre and Anticentre  to be related to the insterstellar absorption, more important towards the Galactic Centre (Lucke 1978)
Be star’s spectral-type distribution
in the cones of COROT
(Frémat, Neiner, Hubert, Floquet, Zorec, Janot-Pacheco, de Medeiros, 2005, submitted)
CorotWeek8 May 2005
Hubert/Neiner

8.  Preparatory programmes for faint Be stars
Detection of Be stars in the exoplanet fields
Spectroscopy at ESO with VLT/GIRAFFE
Part of a programme on the Guaranteed Time Observations of the Observatoire de Paris devoted to spectral classification and precise type identification in exoplanet fields of COROT (G. Alecian: P.I., Hubert, Deleuil, Neiner, Martayan, Floquet):
To validate the method of spectral classification for exoplanet stellar database
(Deleuil et al.)
To determine fundamental parameters
To identify specific groups of stars, Hg-Mn, Be…for Additional Programmes of COROT
CorotWeek8 May 2005
Hubert/Neiner

9. Giraffe: a multi-object spectrograph
CorotWeek8 May 2005
Hubert/Neiner

10. VLT-GIRAFFE: a multi-object spectrograph
In Medusa mode: 132 fibers
R=7500 and
Required astrometric precision : 0.2”
Field =25’
Fibers: Minimal separation ~ 12”
CorotWeek8 May 2005
Hubert/Neiner

11. 2 GIRAFFE fields observed (=26’) next to HD 49933+HD 49434
 Anticentre direction
2 GIRAFFE fields observed (=26’)
next to HD HD 49434
About 35 B0-A5 candidates in each
field (exodat catalog by Deleuil et al.)
2 Be
31 B0-A0 (Teff ≥ 9500°K) H
(Alecian, Martayan et al. in preparation)
CorotWeek8 May 2005
Hubert/Neiner

12. Fundamental parameters B stars:
-LTE temperature and pressure
distributions (ATLAS9, Kurucz)
-NLTE level populations
(TLUSTY, Hubeny & Lanz)
Teff=13615°K, log g=3.95
V sini=65 km/s, RV=49 km/s
Example of fit for a B star:
: observed spectrum
: fitted spectrum
CorotWeek8 May 2005
Hubert/Neiner

13. Be stars: Teff=20860°K, log g=3.93 V sini=260 km/s; RV=55 km/s
CorotWeek8 May 2005
Hubert/Neiner

14. Detection of Be stars in the exoplanet fields…
Photometry at Granada, Spain
uvby + H,H narrow filters (J. Fabregat, Gutierrez-Soto, Suso)
Starting point: emission line stars catalogue of Robertson & Jordan (1989) ( but V<14!)
No information on spectral types is available
Observations at Calar Alto (Almeria, Spain)
Provide spectral classification for RJHA stars
Find new Be stars in exoplanet fields
CorotWeek8 May 2005
Hubert/Neiner

15. Diagram without reddening [m1]-[c1]
Photometry of emission line stars in potential exoplanet fields to identify B stars
Diagram without reddening [m1]-[c1]
5 emission line stars of RJ are B stars
(from Fabregat et al , CorotWeek 4)
CorotWeek8 May 2005
Hubert/Neiner

16. IR photometry with Spitzer
- 4 fields observed with IRAC: 2 at HD , 2 at HD52265
- 4 IR colors (3.6, 4.5, 5.8 et 8.0 mm) for each field
+ JHK colors from 2MASS
+ visible colors and extinction from the exoplanets WG
4 Corot CCDs
2 Spitzer fields
CorotWeek8
Hubert/Neiner

17. 2 fields next to HD
CorotWeek8 May 2005
Hubert/Neiner

18. 2 fields next to HD 52265
CorotWeek8 May 2005

19. Examples Possible Be star observed with Spitzer Typical Be star SED
2MASS Be
Black-body B B
IR excess
(Neiner et al. in preparation)
Spitzer colors
CorotWeek8 May 2005
Hubert/Neiner

20. Next Future… Characterization of bright Be stars almost finished
Search for faint Be stars still in progress
a small number of detections only!
But new data!
VLT/GIRAFFE spectra (Centre direction), SPITZER data
And new proposals!
-WFI + ubvyr and H filters at INT, Canaries
(Fabregat, Neiner, Gutierrez-Soto et al.)
- spectroscopy T1.6m at LNA and T4m-SOAR, (R=6000, visible + R=3000, IR), Brazil + Chile
(Janot-Pacheco, Andrade)
We need positions of hot stars from exoplanet database!
CorotWeek8 May 2005
Hubert/Neiner