COUPLED LINE-PROFILE AND CONTINUUM VARIATIONS IN EZ CANIS-MAJORIS - IMPLICATIONS FOR THE DRIVING MECHANISM OF GLOBAL WIND STRUCTURES IN WOLF-RAYET WINDS

EZ CMa is an apparently unusual Wolf-Rayet star of the nitrogen sequen ce that exhibits strong variations on a period of 3.77 days with coher ency lasting typically about 10 cycles. We have used an extensive set of optical spectroscopic observations to investigate a possible link b etween its line-profile and photometric continuum variability. Despite the strong epoch dependency of the variations, a persistent correlati on is found between changes in the wind line profiles (N v gimel gimel 4604, 4620 in particular) and in continuum flux emanating near the st ellar core. We suggest that these observations give further support to the idea that the physical conditions prevailing in the vicinity of t he star's photosphere have a significant impact on the wind structure and that a spatial dependence of these conditions at the base of the o utflow induces the formation of azimuthal wind structures in EZ CMa. T he epoch-dependent nature of the variability could be related to long- term behavior of corotating magnetic structures, although pulsational instabilities constitute a viable alternative.