Modeling the colliding-wind spectra of theWC8+O7.5III binary gamma-2 Velorum

The bright Wolf-Rayet binary gamma-2 Velorum is one of the few such systems with a resolved orbit. As the nearest one which also shows evidence of colliding winds it offers the potential to be something of a Rosetta stone for understanding Wolf-Rayet stars in general and colliding wind phenomenon in particular. Several years ago, over 500 high-resolution optical spectra of the system were obtained, providing a data set that is remarkable not only for its’ size but also in that over half the data were obtained by amateur astronomers. The C III 5696 line presents excess emission, the shape, location, and strength of which vary with phase. Interpreting this variable excess emission as arising from a colliding wind region, we model the line and present initial results which will be the second in a series of studies resulting from our pro-am campaign.