THE NATURE OF THE WOLF-RAYET PHENOMENON: MASS LOSS CLOSE TO THE EDDINGTON LIMIT

With the new Potsdam Wolf-Rayet (PoWR) hydrodynamic atmosphere models we have obtained the first fully self-consistent wind models for WR stars. We find that WR-type mass loss is initiated when stars approach the Eddington limit. For the most massive stars this happens already at the end of their main-sequence lifetime. i.e. still in the H-burning phase. Less massive objects enter the Wolf-Rayet stage after the onset of He-burning. From spectral analyses with hydrodynamic models we estimate the masses of two extremely luminous, H-rich WNL stars in Carina OB 1. With present masses of at least, 80 100 M., these stars are the direct, descendants of the most massive stars in the galaxy.