CorotWeek8 May 2005 Hubert/Neiner
Corot Be stars groupBe stars:
Secondary targets candidates for the Core Programmeof asteroseismology
Targets for the Additional Programme
The team: 11 members (Belgium, Brazil, France and Spain)
People interested in joining our group are welcome!
Contact: [email protected]: http://www.ster.kuleuven.ac.be/~coralie/corotbe.html
CorotWeek8 May 2005 Hubert/Neiner
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 fieldsCandidates for asteroseismology (long runs)
CorotWeek8 May 2005 Hubert/Neiner
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
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
Fastrot
Assumes:
-Rigid rotator (Roche model)‡ log g
-von Zeipel law‡ Teff
Local model atmospheres
- LTE temperature and pressure distributions (ATLAS 9, Kurucz)
- NLTE level populations (TLUSTY, Hubeny & Lanz)
CorotWeek8 May 2005 Hubert/Neiner
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 0.10V 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 0.10V sini = 325 30 km/s, i ~ 60°
: observed spectrum: fitted spectrum
CorotWeek8 May 2005 Hubert/Neiner
With corrections for/c=0.9
Without correction for rotational effects
Location of Be stars in the HRdiagram
CorotWeek8 May 2005 Hubert/Neiner
Be star’s spectral-type distributionin the cones of COROT
(Frémat, Neiner, Hubert, Floquet, Zorec, Janot-Pacheco, de Medeiros, 2005, submitted)
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)
CorotWeek8 May 2005 Hubert/Neiner
Detection of Be stars in the exoplanet fields
Spectroscopy at ESO with VLT/GIRAFFEPart 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
Preparatory programmes for faint Be stars
CorotWeek8 May 2005 Hubert/Neiner
Giraffe: a multi-object spectrograph
CorotWeek8 May 2005 Hubert/Neiner
VLT-GIRAFFE: a multi-object spectrograph
In Medusa mode: 132 fibers
R=7500 and 25000
Required astrometric precision : 0.2”
Field =25’
Fibers: Minimal separation ~ 12”
CorotWeek8 May 2005 Hubert/Neiner
Anticentre direction
2 GIRAFFE fields observed (=26’)next to HD 49933+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
Fundamental parametersB stars:
-LTE temperature and pressure distributions (ATLAS9, Kurucz)
-NLTE level populations (TLUSTY, Hubeny & Lanz)
Example of fit for a B star: : observed spectrum: fitted spectrum
Teff=13615°K, log g=3.95
V sini=65 km/s, RV=49 km/s
CorotWeek8 May 2005 Hubert/Neiner
Be stars:
Teff=20860°K, log g=3.93 V sini=260 km/s; RV=55 km/s
Teff=15100°K, log g=3.40 V sini=297 km/s; RV=59 km/s
CorotWeek8 May 2005 Hubert/Neiner
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)o Provide spectral classification for RJHA starso Find new Be stars in exoplanet fields
Detection of Be stars in the exoplanet fields…
Photometry at Granada, Spain
CorotWeek8 May 2005 Hubert/Neiner
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. 2003, CorotWeek 4)
CorotWeek8 Hubert/Neiner
IR photometry with Spitzer
- 4 fields observed with IRAC: 2 at HD49933+49434, 2 at HD52265- 4 IR colors (3.6, 4.5, 5.8 et 8.0 m) for each field
+ JHK colors from 2MASS+ visible colors and extinction from the exoplanets WG
4 Corot CCDs
2 Spitzer fields
CorotWeek8 May 2005 Hubert/Neiner
2 fields next to HD 49933+49434
CorotWeek8 May 2005 Hubert/Neiner
2 fields next to HD 52265
CorotWeek8 May 2005 Hubert/Neiner
Spitzer colors
IR excess
Examples
Typical Be star SED Possible Be star observed with Spitzer
B
Be
2MASS
Black-body B
(Neiner et al. in preparation)
CorotWeek8 May 2005 Hubert/Neiner
Next Future… Characterization of bright Be stars almost finished
Search for faint Be stars still in progressa 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!