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Summary: 1
XMM OBSERVATIONS OF THE WR+O SYSTEM GAMMA VELORUM
T. Dumm 1 , M.Gudel 2 , W. Schmutz 3 , M.Audard 2 , H. Schild 1 , M. Leutenegger 4 , and K. van der Hucht 5
1 Institute for Astronomy, ETH Zentrum, CH-8092 Zurich, Switzerland
2 Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
3 Physikalisch-Meteorologisches Observatorium Davos, CH-7260 Davos Dorf, Switzerland
4 Department of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA
5 Space Research Organization Netherlands, NL-3584 Utrecht, The Netherlands
Abstract
We present XMM-Newton observations of the system
Velorum at the two phases 0.1 and 0.4. The variation of
the hard X-rays are interpreted as due to occultation by
the WR wind. From a comparison of the observed inten-
sity ratio to one predicted by an unclumped wind model
we derive a clumping factor of 16 for the WR wind. We
unequivocally identify two X-ray emitting regions: The
shock zone of colliding stellar winds with temperatures
up to 25 MK and a photoionized region with T e < 60 kK.
The revealing detection of the photoionized region is a
narrow radiative recombination continuum of C vi at 25.3
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