Are Wolf-Rayet winds driven by radiation?

Abstract

Recent results with the Potsdam Wolf-Rayet (PoWR) models have shown that Wolf-Rayet mass loss can be explained by radiative wind driving. An inspection of the galactic WR sample, however, reveals that a significant part of the observed WR stars are in conflict with our models. This group is chiefly formed by intermediate spectral subtypes. Among the population of late-type WN stars we find that the enigmatic WN8 subtypes, which are well-known for their photometric variations, are in disagreement with our models. So are there other driving mechanisms working in these objects?

8 pages, to appear in "Mass loss from stars and the evolution of stellar clusters". Proc. of a workshop held in honour of H.J.G.L.M. Lamers, Lunteren, The Netherlands. Eds. A. de Koter, L. Smith and R. Waters (San Francisco: ASP)