2004A&A...423..267G

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 γ² Vel are used to illustrate how the model predictions can be applied to the observational data.