Corot Be stars group Be stars Secondary targets
Corot Be stars group ØBe stars: üSecondary targets candidates for the Core Programme of asteroseismology üTargets for the Additional Programme ØThe team: 11 members (Belgium, Brazil, France and Spain) People interested in joining our group are welcome! ØContact: coralie@ster. kuleuven. be Website: http: //www. ster. kuleuven. ac. be/~coralie/corotbe. html Corot. Week 8 May 2005 Hubert/Neiner
Be stars as potential targets for the Additional Programme Ø Science goal for Be stars: ü 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) ü Faint Be stars with 12<V<16. 5 in the exoplanet fields Candidates for asteroseismology (long runs) Corot. Week 8 May 2005 Hubert/Neiner
Preparatory programs for bright Be stars ü Photometric variability Strömgren photometry (0. 9 m-T in Granada) : periodicity in early Be stars candidates (Gutierrez-Soto et al. 2003) and even multiperiodicity for NW Ser and V 1446 Aql (Fabregat, this COROTWeek) ü Spectroscopic variability (LNA + OHP+ multisite) ü Determination of fundamental parameters taking into account fast rotation and veiling (Frémat, et al. 2005) ü Search for magnetic fields (Es. Pa. Do. NS, CFHT) Corot. Week 8 May 2005 Hubert/Neiner
ØDetermination of stellar parameters ü Data : GAUDI + OHP + LNA + FEROS ü 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 (ATLAS 9, Kurucz) - NLTE level populations (TLUSTY, Hubeny & Lanz) ü CS envelope veiling effect Corot. Week 8 May 2005 Hubert/Neiner
ü 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° Corot. Week 8 May 2005 : observed spectrum : fitted spectrum Hubert/Neiner
Location of Be stars in the HR diagram Without correction for rotational effects With corrections for / c=0. 9 Corot. Week 8 May 2005
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) Corot. Week 8 May 2005 Hubert/Neiner
Preparatory programmes for faint Be stars ØDetection of Be stars in the exoplanet fields ü 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 Corot. Week 8 May 2005 Hubert/Neiner
Giraffe: a multi-object spectrograph Corot. Week 8 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” Corot. Week 8 May 2005 Hubert/Neiner
Anticentre direction 2 GIRAFFE fields observed ( =26’) next to HD 49933+HD 49434 About 35 B 0 -A 5 candidates in each field (exodat catalog by Deleuil et al. ) Ø 2 Be Ø 31 B 0 -A 0 (Teff ≥ 9500°K) H (Alecian, Martayan et al. in preparation) Corot. Week 8 May 2005 Hubert/Neiner
Fundamental parameters B stars: -LTE temperature and pressure distributions (ATLAS 9, Kurucz) -NLTE level populations (TLUSTY, Hubeny & Lanz) ØTeff=13615°K, log g=3. 95 V sini=65 km/s, RV=49 km/s Corot. Week 8 May 2005 Example of fit for a B star: : observed spectrum : fitted spectrum Hubert/Neiner
Be stars: ØTeff=20860°K, log g=3. 93 V sini=260 km/s; RV=55 km/s ØTeff=15100°K, log g=3. 40 V sini=297 km/s; RV=59 km/s Corot. Week 8 May 2005 Hubert/Neiner
ØDetection of Be stars in the exoplanet fields… üPhotometry 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) o Provide spectral classification for RJHA stars o Find new Be stars in exoplanet fields Corot. Week 8 May 2005 Hubert/Neiner
Photometry of emission line stars in potential exoplanet fields to identify B stars Diagram without reddening [m 1]-[c 1] 5 emission line stars of RJ are B stars (from Fabregat et al. 2003, Corot. Week 4) Corot. Week 8 May 2005 Hubert/Neiner
üIR photometry with Spitzer - 4 fields observed with IRAC: 2 at HD 49933+49434, 2 at HD 52265 - 4 IR colors (3. 6, 4. 5, 5. 8 et 8. 0 mm) for each field + JHK colors from 2 MASS + visible colors and extinction from the exoplanets WG 4 Corot CCDs Corot. Week 8 Hubert/Neiner 2 Spitzer fields
2 fields next to HD 49933+49434 Corot. Week 8 May 2005 Hubert/Neiner
2 fields next to HD 52265 Corot. Week 8 May 2005
Examples Typical Be star SED Possible Be star observed with Spitzer 2 MASS Be Black-body B B IR excess (Neiner et al. in preparation) Corot. Week 8 May 2005 Spitzer colors Hubert/Neiner
Next Future… üCharacterization of bright Be stars almost finished ü 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 T 1. 6 m at LNA and T 4 m-SOAR, (R=6000, visible + R=3000, IR), Brazil + Chile (Janot-Pacheco, Andrade) We need positions of hot stars from exoplanet database! Corot. Week 8 May 2005 Hubert/Neiner
- Slides: 20