AAS 199th meeting, Washington, DC, January 2002
Session 135. Circumstellar Material and Atmospheres: Hotter
Display, Thursday, January 10, 2002, 9:20am-4:00pm, Exhibit Hall

## [135.16] The massive star O+WR binary \gamma Velorum

O. De Marco (American Museum of Natural History), A.J. Willis, S.R. Colley (University College London)

The \gamma Vel O+WR binary system is known to have colliding winds from its X-ray properties. Here we use the stellar parameters of the two stars in the system, derived from the non-LTE models of De Marco & Schmutz (2000) and De Marco et al. (2000), to aid in the interpretation of the optical line variability in terms of the geometry and distribution of the gas around the two stars.

We find that the rich dataset (high signal-to-noise ratio, high resolution optical spectra finely sampling the orbital period) allows a very accurate determination of the opening angle of the wake formed as the WR wind impacts the O star. This can lead to understanding whether radiative breaking (of the WR wind gas by the O star radiation field) is efficient in this system. From the location of the emission line forming regions within the WR wind (from the non-LTE models), and the variability patterns of those lines, it is possible to construct a detailed map of the WR wind.

Work financed by the Asimov Fellowship program of the Americam Museum of Natural History.