Natal 2004/11/011st Brazil-CoRoT meeting1 Seismology of Be stars with CoRoT Paris-Meudon Observatory: A.M. Hubert, M. Floquet, C. Neiner* Univ. of Valencia: J. Fabregat, J. Gutierrez-Soto, J. Suso Univ. of Sao Paulo: E. Janot-Pacheco, L. Andrade, S. Daflon Royal Observatory of Belgium: Y. Frémat *ESA, Estec, RSSD

Natal 2004/11/011st Brazil-CoRoT meeting2 Seismology of Be stars with CoRoT Overview of Be stars Be stars as non radial pulsators What do we expect from COROT? Preparatory programmes  in “seismo“ fields  in “exoplanet“ fields Conclusion

Natal 2004/11/011st Brazil-CoRoT meeting3 Be stars: main characteristics Population: about 20% of all B-type stars Main sequence or slightly evolved Usually rapidly rotating stars (  c ≥ 0.80) Equatorially concentrated envelope Discrete mass loss events: unknown origin Variability: NRP+ stellar and circumstellar activity Be phase: non permanent character

Natal 2004/11/011st Brazil-CoRoT meeting4 Variability in Be stars… Short-term variability present in the quasi-totality of early Be stars, in ~ 50% of mid-types (B4-B5e) and in only 18% of late Be stars (Hipparcos data, Hubert & Floquet 1998) Short periods commonly detected in photometry and spectroscopy Multiperiodicity in light curves and line profiles e.g.  Oph (O9.5Ve), Jankov, Janot-Pacheco, Leister 2000 and MOST data; 19 Mon (B1Ve), Neiner, Hubert, Floquet 2003; Balona et al. 2002

Natal 2004/11/011st Brazil-CoRoT meeting5 Example of multiperiodicity in light curves 19 Mon Upper panel:folded in phase with P 1 =0.191d  Lower panel: folded in phase with P 2 =0.204d after removing P 1  NB: P 1 and P 2 also found from ground-based data by Balona et al Variation of the magnitude of 19 Mon from Hipparcos data.

Natal 2004/11/011st Brazil-CoRoT meeting6 Be stars as non-radial pulsators…   Cephei, SPB (Slow Pulsating B stars), Be stars  Same instability domain (  mechanism)  Line profiles modelling support NRP (e.g. Rivinius et al. 2002, Neiner et al. 2004)

Natal 2004/11/011st Brazil-CoRoT meeting7 Be stars as non-radial pulsators… NRP: trigger for discrete mass loss events?  only one case:  Cen, 15 years of spectroscopic observations: coincidence of positive mode interference and mass loss events (Rivinius et al. 1998) 6 periods sorted in 2 groups main mode of each period group: P1=0.5029dl=2, |m|=2  f=0.21, 0.39, 0.60  Hz P5=0.2814dl=3, |m|=3  f=0.33  Hz

Natal 2004/11/011st Brazil-CoRoT meeting8  Cen : pulsation beating effect Rivinius et al., 1998 The overall reconstructed amplitude (solid lines); circles:   ; squares:   ; dots:  

Natal 2004/11/011st Brazil-CoRoT meeting9 Be stars as magnetic pulsators Magnetically pulsating stars?  2 detections among pulsating early B stars:  Cep (Henrichs et al. 2000): also a slowly rotating Be star! P rot =12d; P puls =0.19d  Ori (Neiner et al. 2003): a « classical » Be star P rot =1.29d; P puls =0.97d magnetic fields: several hundreds of Gauss

Natal 2004/11/011st Brazil-CoRoT meeting10 Observed frequencies in  Cep (Telting et al. 1997) f 3 =  Hz f 4 =  Hz f 1 =  Hz f 5 =  Hz f 6 =  Hz f 2 =  Hz magnetic splitting + identification of modes  information on the evolutionary stage ( Shibahashi & Aerts, 2000) - Quintuplet fine structure of a radial mode (f 1 ) - f 2  non radial mode (l=2,m=0) }

Natal 2004/11/011st Brazil-CoRoT meeting11 Seismology with COROT Homogenous data Long-term continuous coverage:  high accuracy on frequency spectrum - multimode detection - beating  it will allow us to disentangle pulsations from stellar activity (temporarily corotating clouds) Very high photometric accuracy :  detection of high degree modes of low amplitude Amp 4 in early Be stars (Balona & Kambe 1999)  search of low-amplitude g modes in late Be stars

Natal 2004/11/011st Brazil-CoRoT meeting12 Early and late Be stars: 2 science goals Early Be stars (B0-B3): pulsations and multiperiodicity already detected from the ground  Is the beating effect of close pulsation periods the cause of the Be phenomenon i.e. the presence of a disk around Be stars?  Effects of fast rotation and magnetic field on the pulsations Late Be stars (B4-B9): pulsations predicted by theory but the amplitude is too small to be detected from the ground  detection of pulsations with Corot!

Natal 2004/11/011st Brazil-CoRoT meeting13 Be stars as potential targets for asteroseismology with COROT 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) 18 Be stars as secondary targets candidates for the core programme of asteroseismology Faint Be stars with 12<V<16.5 in the exoplanet fields as part of the Additional Programme

Natal 2004/11/011st Brazil-CoRoT meeting14  Preparatory programmes in “seismo“ fields Be stars as secondary targets candidates in primary fields (long runs)  Photometric variability: periodicity, multiperiodicity  Spectroscopic variability: pulsation modes  Determination of fundamental parameters taking into account fast rotation - Abundances  Search of magnetic fields (EsPaDoNS, CFHT) Be stars for exploratory fields (short runs)

Natal 2004/11/011st Brazil-CoRoT meeting15 Photometric variability: Hipparcos (Hubert & Floquet )  Some of the targets observed by Hipparcos: periodicity found!

Natal 2004/11/011st Brazil-CoRoT meeting16 Ground-based photometry + variability (Fabregat, Gutierrez-Soto, Suso)  Strömgren photometry at the 0.9m in Granada for variability: detection of variability, periodicity and even multiperiodicity for HD and HD  NB: HD has been in a B phase for several years!

Natal 2004/11/011st Brazil-CoRoT meeting17 Spectroscopy: GAUDI  for 6 < V < 8  spectra in GAUDI  17 new Be stars discovered in GAUDI But:  No spectrum if V > 8  Additional data for studying variability and determining fundamental parameters are needed

Natal 2004/11/011st Brazil-CoRoT meeting18 Additional spectroscopy + variability (Hubert, Janot-Pacheco, Andrade)  Spectroscopic observations at the 1.5m at OHP, soon EsPaDoNS  Spectroscopic observations at the 1.6m at LNA, FEROS  Spectrum for Be stars with V > 8  Detection of variability

Natal 2004/11/011st Brazil-CoRoT meeting19 Determination of stellar parameters ( Frémat, Neiner, Daflon, Andrade)  Data : GAUDI + OHP + LNA  2 independent determinations: Frémat & Neiner + Daflon & Andrade  ~70 Be stars in the eyes of Corot

Natal 2004/11/011st Brazil-CoRoT meeting20 Rapid rotation  gravitational darkening effects

Natal 2004/11/011st Brazil-CoRoT meeting21 (Frémat & Zorec)

Natal 2004/11/011st Brazil-CoRoT meeting22 Centre Main targetBe targetTypeVvsiniTefflog gVariability HD HD B8e HD HD B8e HD HD B9IIIe HD HD HD B9Ve HD B8e  Only late Be stars in these primary targets fields. Results for primary fields

Natal 2004/11/011st Brazil-CoRoT meeting23 Anticentre Main targetBe targetTypeVvsiniTefflog gVariability HD HD 43587HD 43285B6Ve d HD 43913A0e7.88 HD HD 46558HD 45901B2Ve phot HD 46484B1Ve d HD 47359B0.5Ve8.87 HD HD 49330B0e d HD 49585B0.5Ve d HD 50209B9Ve d HD 50696B1Ve d HD 52265HD 50891B0pe d HD 51193B1Vnne d HD 51404B3e d HD 51452B0IIIne spec

Natal 2004/11/011st Brazil-CoRoT meeting24 Centre:  4 possible late Be stars including 3 well positioned next to the primary targets  no early Be stars Anticentre:  3 possible late Be stars well positioned next to the primary targets  10 possible early Be stars including 3 well positioned next to HD TOTAL: 17 possible Be stars (7 late, 10 early) including 9 well positioned (6 late and 3 early)

Natal 2004/11/011st Brazil-CoRoT meeting25 Field HD HD

Natal 2004/11/011st Brazil-CoRoT meeting26 Diapositive 29 Field HD HD  3 early Be stars outside the CCDs with this position of the CCDs

Natal 2004/11/011st Brazil-CoRoT meeting27 Field HD HD

Natal 2004/11/011st Brazil-CoRoT meeting28 HR diagram of Be secondary targets Rotation effect  c = Be stars

Natal 2004/11/011st Brazil-CoRoT meeting29 Results for exploratory fields  ~ 60 possible Be targets for exploratory fields (short runs)  It is better to concentrate on early Be stars, since we have very few early Be stars as secondary targets  2 already detected with multiperiodicity (Fabregat et al.) : HD (B3e) and HD (B5e)  Targets in non-selected primary fields have been well studied  easier candidates

Natal 2004/11/011st Brazil-CoRoT meeting30  Preparatory programmes in exoplanet fields Be stars as targets for seismology in exoplanet fields (12<V<16)  Detection of Be stars in selected fields (in progress); two methods: photometry and spectroscopy  Determination of fundamental parameters  Selection of the “best “ candidates (early Be stars)

Natal 2004/11/011st Brazil-CoRoT meeting31 Detection of Be stars in the exoplanet fields uvby photometry + H ,H  narrow filters by J. Fabregat and collaborators:  Starting point: emission line stars catalogue of Robertson & Jordan (1989)  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

Natal 2004/11/011st Brazil-CoRoT meeting32 Photometry of emission line stars in potential exoplanet fields to identify B stars Diagramme without reddening [m 1 ]-[c 1 ] 5 emission line stars of RJ are B stars

Natal 2004/11/011st Brazil-CoRoT meeting33 At least 4 of 5 B emission line stars are confirmed and are probably Be stars + 1 more discovered Diagramme  -  N.B.: Robertson-Jordan stars limited to V<14!

Natal 2004/11/011st Brazil-CoRoT meeting34 Detection of Be stars in the exoplanet fields Spectroscopy at LNA (see poster Andrade & Janot) 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., Deleuil, Hubert et al.):  To validate the method of spectral classification for exoplanet stellar database  To determine fundamental parameters  To identify specific groups of stars, Hg-Mn, Be…for Additional Programmes of COROT

Natal 2004/11/011st Brazil-CoRoT meeting35 Giraffe: a multi-object spectrograph

Natal 2004/11/011st Brazil-CoRoT meeting36 VLT-GIRAFFE: a multi-object spectrograph In Medusa mode: 132 fibers R=7500 and Required astrometric precision : 0.2” Field  =25’ Fibers: Minimal separation ~ 12”

Natal 2004/11/011st Brazil-CoRoT meeting37 Search for Be stars with VLT-GIRAFFE Domains:  LR06 (644nm - 710nm; R=8600): H  - emission line stars:Be, Ae/Be…  LR02 (397nm - 456nm; R=6400): H , H , blue He I, Mg II - stellar types and fundamental parameters For B9 stars, 1h exposure time, V= 15, S/N  100

Natal 2004/11/011st Brazil-CoRoT meeting38 Expected detection of Be stars in the exoplanet fields Centre direction ~ 40 Be stars (12<V<16) in 1 deg 2 Exoplanet CCDs ~1.3x2.5 deg 2 Anti-centre direction ~ 10 Be stars (12<V<16) in 1 deg 2 Exoplanet CCDs ~1.3x2.5 deg 2 from estimation of stellar density in 1 deg 2 towards the galactic centre and anti-centre given by M. Deleuil and from the ‘Besançon’ model of stellar population synthesis of the Galaxy (Robin et al. 2003)

Natal 2004/11/011st Brazil-CoRoT meeting39 Conclusions  We need early and late Be stars as secondary targets: 2 different science goals  We have 9 out of 17 Be stars (possible secondary targets) which are well positioned in the CCDs, but 6 late and only 3 early  We need to concentrate on early Be stars for the exploratory fields  We already have 2 very interesting exploratory candidates  The list of faint Be stars for seismology is in preparation; it depends on the final choice of the position of the CCDs