Corot Be stars group

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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_at_ster.kuleuven.be
• Website http//www.ster.kuleuven.ac.be/coralie/c
  orotbe.html

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Be stars as potential targets for the Additional
Programme

• Science goal for Be stars
• About 70 Be stars with 6ltVlt9.5 in the cones of
  COROT (seismology fields) including 15 new Be
  stars with Vlt8.0 (GAUDI) (Neiner, Hubert, Catala
  2005)
• Candidates for pulsations, rotation, activity,
  binarity studies (short runs)
• Faint Be stars with 12ltVlt16.5 in the exoplanet
  fields
• Candidates for asteroseismology (long runs)

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? 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)

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• 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

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• From modeling of different spectral domains ?
  Teff, logg, Vsin i and i for a given ?/?c

Without correction for rotational effects Teff
25450 ? 1000K, 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 ? 1000K, log g 4.10 ? 0.10 V sini 325
? 30 km/s, i 60
observed spectrum fitted spectrum
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Location of Be stars in the HR diagram
Without correction for rotational effects
With corrections for ?/?c0.9
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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 stars spectral-type distribution in the cones
of COROT
(Frémat, Neiner, Hubert, Floquet, Zorec,
Janot-Pacheco, de Medeiros, 2005, submitted)
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? 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,
  Befor Additional Programmes of COROT

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Giraffe a multi-object spectrograph
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VLT-GIRAFFE a multi-object spectrograph
In Medusa mode 132 fibers R7500 and
25000 Required astrometric precision
0.2 Field ?25 Fibers Minimal separation
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? Anticentre direction
2 GIRAFFE fields observed (?26) next to HD
49933HD 49434 About 35 B0-A5 candidates in each
field (exodat catalog by Deleuil et al.)

• 2 Be
• 31 B0-A0 (Teff 9500K)

H?
(Alecian, Martayan et al. in preparation)
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Fundamental parameters B stars -LTE temperature
and pressure distributions (ATLAS9,
Kurucz) -NLTE level populations (TLUSTY, Hubeny
Lanz)

• Teff13615K, log g3.95
• V sini65 km/s, RV49 km/s

Example of fit for a B star observed
spectrum fitted spectrum
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• Be stars

• Teff20860K, log g3.93
• V sini260 km/s RV55 km/s

• Teff15100K, log g3.40
• V sini297 km/s RV59 km/s

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• 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 Vlt14!)
• 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

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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)
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• IR photometry with Spitzer

- 4 fields observed with IRAC 2 at
HD4993349434, 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
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2 fields next to HD 4993349434
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2 fields next to HD 52265
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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
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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,
  (R6000, visible R3000, IR), Brazil Chile
• (Janot-Pacheco, Andrade)

We need positions of hot stars from exoplanet
database!