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Topics addressed in this talk:

Possible contributions of the Groupe d’Astrophysique des Hautes Energies (GAPHE) to the GAIA data processing Eric Gosset, Gregor Rauw, Yaël Nazé & Hugues Sana Institut d’Astrophysique et de Géophysique, Université de Liège. Topics addressed in this talk:.

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Topics addressed in this talk:

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  1. Possible contributions of the Groupe d’Astrophysique des Hautes Energies (GAPHE) to the GAIA data processingEric Gosset, Gregor Rauw, Yaël Nazé & Hugues SanaInstitut d’Astrophysique et de Géophysique, Université de Liège

  2. Topics addressed in this talk: • The GAPHE and its research activities related to early-type stars • Orbital solutions for spectroscopic binaries • GAIA support observations of early-type stars from the ground • Photometric studies of Wolf-Rayet stars

  3. 1. The GAPHE and its research activities related to early-type stars • Currently (February 2006) the GAPHE consists of 2 senior scientists, 3 post-docs and 2 PhD students mainly working on high-energy data • 76 publications (50 in refereed journals) related to early-type stars over the last five years. • Many successful proposals on ground-based (ESO, OHP, CTIO, VLA) and spaceborne (XMM-Newton, Chandra, INTEGRAL) facilities

  4. Multi-wavelength studies of many categories of early-type stars: • Normal O stars: e.g.CPD – 41° 7742 (O9V + B1-1.5V, Sana et al. 2003, 2005, X-rays + optical)… • Peculiar Of stars: e.g.BD +60° 2522 (Oef, Rauw et al. 2003, optical), HD 108 (Of?p, Nazé et al. 2001, 2004, X-rays + optical), • Wolf-Rayet stars: e.g. WR 40(WN8, Gosset et al. 2005, X-rays + optical),WR 20a(WN6ha + WN6ha, Rauw et al. 2004, 2005, optical) • B[e] stars: e.g.He 3-209(Nazé et al. 2006, optical) • LBVs: e.g.HD 5980(Nazé et al. 2002, 2003, 2004, X-rays) • Non-thermal radio emitters: e.g.9 Sgr(O4 V + O7-8V, Rauw et al. 2002, 2005, X-rays + radio + optical),Cyg OB2 #8a(O6f + O5.5(f), De Becker et al. 2004, 2005, 2006, X-rays + gamma-rays + optical + radio), • …

  5. Some science topics addressed by our team • High-energy properties of early-type stars • Fundamental properties of early-type stars in binaries • The colliding wind phenomenon in massive binaries • Non-thermal phenomena in stellar winds • Massive stars and their surroundings (He II nebulae, wind-blown bubbles and star formation processes in young open clusters) • Intrinsic variability of (presumably) single early-type stars

  6. High energy properties of early-type stars XMM-Newton and INTEGRAL studies of the X-ray and soft gamma-ray emission from clusters of massive stars:

  7. Fundamental properties of early-type stars in binaries… Massive binaries in young open clusters: • NGC 6231, Trumpler 16 and IC 1805 : study of early-type binaries and hierarchical triple systems, analysis of spectroscopic orbital solutions and photometric eclipses  accurate absolute parameters

  8. …and the colliding wind phenomenon Optical and X-ray monitoring of a sample of colliding wind binaries in various evolutionary stages from OV to WR: optical line profile variability, X-ray flux modulations and hydro simulations  constraints on the mass loss rates and physics of stellar winds

  9. 2. Orbital solutions for spectroscopic binaries • A large fraction of the stars in our Galaxy (about 50% depending on the spectral type) are binary systems. • Depending on the orbital period and inclination, they may be seen as spectroscopic binaries. • The RVS instrument onboard GAIA will provide radial velocity measurements for a huge number of binaries  need to use an efficient algorithm to handle this large set of data. The method also needs to be robust, i.e. able to deal with all sorts of binary systems (early-type, late-type, interacting binaries…) Depending on the available manpower, we intend to test and implement different methods (for instance based on genetic algorithms) on a large number of real and simulated data.

  10. Some peculiar problems with the orbital solution of early-type binaries… • Due to the expanding motion of the stellar wind, different spectral lines that are formed in the wind yield different apparent systemic velocities (similar problems occur for cataclysmic variables and X-ray binaries)  foresee the possibility of different apparent systemic velocities

  11. 3. GAIA support observations of early-type stars from the ground • High-resolution spectroscopic observations of early-type stars of all sorts of spectral types (WN, WC, Of, O,…) either over the RVS spectral domain or over a broader wavelength range. • These observations should complement the data set of Munari & Tomasella (1999, A&AS 137, 521) We have a large set of high-resolution FEROS data at our disposal and we are conducting spectroscopic surveys at OHP (Elodie and Aurelie spectrographs) and ESO (FEROS).

  12. 4. Photometric studies of Wolf-Rayet stars • Narrow-band photometric filters allow to identify Wolf-Rayet stars (Royer et al. 2001, A&A 366, L1) and to discriminate between different WR-subtypes.

  13. 4. Photometric studies of Wolf-Rayet stars • Narrow-band photometric filters allow to identify Wolf-Rayet stars (Royer et al. 2001, A&A 366, L1) and to discriminate between different WR-subtypes. • Synthetic photometry (see Royer et al. 1998, A&AS 130, 407) can be used to evaluate the capabilities of the GAIA photometric system in this respect. • Our team has a large experience in photometric variability studies of WR stars (in particular for the interpretation of variations in the emission lines and in the continuum). Our team has a long-standing experience in the simulation of narrow-band photometry of Wolf-Rayet stars and in the interpretation of the photometric variability of these stars.

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