Abstract

Massive stars close to the Eddington limit: Mass loss and envelope inflation.

Goetz Graefener (Armagh Observatory)

J.S. Vink (Armagh Observatory) S.P. Owocki (Bartol Research Institute)

When massive stars are approaching the Eddington limit, their outer envelopes, and winds become dominated by 'opacity peaks', i.e., by material properties. We discuss the physical consequences, namely the formation of strong, Wolf-Rayet (WR) type winds, and a radial extension of the stellar envelopes. Moreover, we present a semi-empirical study of the most massive stars in the Arches cluster, that supports a strong dependence of stellar mass loss on the Eddington factor in this regime. Similar studies, to investigate the transition between O- and WR-type mass loss, are underway within the VLT-FLAMES Tarantula Survey.