EDP Sciences
Free access
Volume 423, Number 1, August III 2004
Page(s) 267 - 279
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:200400030

A&A 423, 267-279 (2004)
DOI: 10.1051/0004-6361:200400030

Line profile variations in WR+O binary systems

I. The code and basic predictions
L. N. Georgiev1 and G. Koenigsberger2

1  Instituto de Astronomía, Universidad Nacional Autónoma de México, México
    e-mail: georgiev@astroscu.unam.mx
2  Centro de Ciencias Físicas, Universidad Nacional Autónoma de México, México
    e-mail: gloria@astroscu.unam.mx

(Received 7 January 2003 / Accepted 13 January 2004)

We compute the P Cyg line profiles formed by the stellar winds of binary systems containing a Wolf-Rayet and an O-type star, incorporating the effects due to wind eclipses and wind-wind collisions. The contribution from both stellar winds to the P Cygni emission lines is modeled for different orbital phases. The opacity and the source function are calculated assuming a simplified atom and the Sobolev approximation, and the emission-line profile is calculated by exact radiative transfer through the 3D geometry wind. We analyze the cases of a P Cygni line that is formed only in the WR wind, and the case of a line formed in both the WR and the O-star winds. The line-profile variations that are predicted by this model are presented. When compared with observations, the synthetic profiles and their phase-dependent variability provide an estimate for the opening angle of the WWC shock cone and the velocity law of both stellar winds. Ultraviolet (UV) observations of the binary system $\gamma^2$ Vel are used to illustrate how the model predictions can be applied to the observational data.

Key words: line: formation -- line: profiles -- radiative transfer -- stars: binaries: general -- stars: Wolf-Rayet

SIMBAD Objects

© ESO 2004