A Lifetime of Influence: Abstracts, Talks, and Posters
 

WR Stars in the Galaxy and the LMC: Analysis, Parameters, and Evolution

Wolf-Rainer Hamann
University of Potsdam, Germany

Adriane Liermann
University of Potsdam, Germany

Ute Ruehling
University of Potsdam, Germany

Conti et al. (1983) had already realized that some of the WN stars (Wolf-Rayet stars of the nitrogen sequence) show hydogen in their spectra, while others seem to be hydrogen-free. More recent quantitative analyses based on elaborate model atmospheres confirm that the hydrogen abundance constitutes a dichotomy between two subclasses, the very luminous "WNL" stars and the less luminous, hydrogen-free "WNE" stars. The former evolve directly from very massive O-type stars - the original "Conti scenario" -, while the latter loop through the red side of the HRD. The modeling of evolutionary tracks depends sensitively on the mass-loss rates in different phases, and also on novel physical ingredients like rotationally induced mixing, or internal magnetic fields. Detailed comparisons of the WR populations in the Galaxy and the LMC with synthetic populations based on existing evolutionary tracks are not yet conclusive.