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Corot Be stars group

Corot Be stars group. Be stars: 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: coralie@ster.kuleuven.be

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Corot Be stars group

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  1. Corot Be stars group • Be stars: • 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:coralie@ster.kuleuven.be Website:http://www.ster.kuleuven.ac.be/~coralie/corotbe.html 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) 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) 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 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 Hubert/Neiner

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

  7. Different Be star spectral distributions between the Galactic Centre and Anticentre  to be related to the insterstellarabsorption, 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) 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 Hubert/Neiner

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

  10. 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” Hubert/Neiner

  11.  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) 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 Hubert/Neiner

  13. 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 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 Hubert/Neiner

  15. 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) Hubert/Neiner

  16. 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 mm) for each field + JHK colors from 2MASS + visible colors and extinction from the exoplanets WG 4 Corot CCDs 2 Spitzer fields Hubert/Neiner

  17. 2 fields next to HD 49933+49434 Hubert/Neiner

  18. 2 fields next to HD 52265

  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 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! Hubert/Neiner

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