Modelling the colliding-wind spectra of the WC8d+O8-9IV binary CV Ser (WR 113)

Striking profile variations of the C III lambda 5696 emission line are visible amongst the high signal-to noise ratio, moderate resolution spectra of the 29.7 d WC8d+O8-9IV binary CV Ser (WR 113) presented here. Using a significantly revised code, we have modelled these variations assuming the emission originates from the undisturbed WR star wind and a colliding wind shock region that partially wraps around the Ostar. Changes to the modelling code are chiefly in the form of additional parameters, intended to refine the modelling and facilitate comparison with recent predictions arising from theoretical and hydrodynamical work. This modelling provides measurements of crucial parameters such as the orbital inclination (63.5 degrees +/- 2.5 degrees) and thus, together with the RV orbits, the stellar masses (11.7 +/- 0.9 M-circle dot for the WR star and 33.3 +/- 2.0 M-circle dot for the O star). We find good agreement with expectations based on theoretical studies and hydrodynamical modelling of colliding wind systems. Moreover, it raises the exciting prospect of providing a reliable method to learn more about WR stellar masses and winds, and for studying the physics of colliding winds in massive stars.