Possible contributions of the Groupe d

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

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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

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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)
• Be 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),

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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

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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

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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

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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

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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.
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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

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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, AAS 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).
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4. Photometric studies of Wolf-Rayet stars

• Narrow-band photometric filters allow to identify
  Wolf-Rayet stars (Royer et al. 2001, AA 366, L1)
  and to discriminate between different WR-subtypes.

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4. Photometric studies of Wolf-Rayet stars

• Narrow-band photometric filters allow to identify
  Wolf-Rayet stars (Royer et al. 2001, AA 366, L1)
  and to discriminate between different
  WR-subtypes.
• Synthetic photometry (see Royer et al. 1998, AAS
  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.