MASS-LOSS FROM WOLF-RAYET STARS DUE TO RADIATION PRESSURE AND ALFVEN WAVES

We discuss the physical mechanism that can explain the observed large mass loss in luminous, Wolf-Rayet (WR) stars. Interpreted classically, the P Cygni line profiles imply that the terminal velocity of the flow is approximately 2500 km s-1. These winds are generally interpreted as radiation pressure line-driven. Radiation pressure line-driven models, however, present difficulties in explaining several observational characteristics of these stars. We investigate, in particular, the disagreement between the observational mass-loss rates in WR stars and the maximum predicted mass loss by radiation pressure. We investigate a model for mass-loss rates from WR stars, where both a flux of Alfven waves and radiation pressure are important in order to reproduce the terminal velocity observed. Our model is a fusion of the Alfven wave wind model of Jatenco-Pereira and Opher and the radiation pressure model of Castor, Abbott, & Klein. Whereas a pure Alfven wave-driven model requires a magnetic field approximately 20,000 G, in our model we find that the required magnetic field is less than 1000 G.