corot be stars group

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: coralie@ster.kuleuven.beWebsite: 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!