TY  - JOUR
A1  - Liermann, A.
T1  - Evolution of Wolf-Rayet spectra
JF  - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015
N2  - Wolf-Rayet stars are important sources for the enrichment of the ISM with nuclear processed elements, UV photons and momentum. They are descendants of high-mass stars for which short lifetimes and transition times can hamper the spectral classification of the stars in their different evolutionary phases. The expanded stellar atmospheres of Wolf-Rayet stars can show spectra which seem inconsistent with the anticipated underlying evolution phase, for example in late hydrogen-burning WN stars and Of/WN transition stars. We present a sequence of synthetic spectra of the Potsdam Wolf-Rayet models based on the latest Geneva stellar evolution models. This will visualize the changes in stellar spectra over a full stellar lifetime. Direct comparison with observed stellar spectra, as well as the evolution of diagnostic line ratios will improve the connection of spectral classification and evolution phase.
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-87830
SP  - 129
EP  - 132
ER  - 
TY  - CHAP
A1  - Liermann, A.
A1  - Hamann, Wolf-Rainer
T1  - Clumping in Galactic WN stars : a comparison of mass loss rates from UV/optical & radio diagnostics
N2  - The mass loss rates and other parameters for a large sample of Galactic WN stars have been revised by Hamann et al. (2006), using the most up-to date Potsdam Wolf-Rayet (PoWR) model atmospheres. For a sub-sample of these stars exist measurements of their radio free-free emission. After harmonizing the adopted distance and terminal wind velocities, we compare the mass loss rates obtained from the two diagnostics. The differences are discussed as a possible consequence of different clumping contrast in the line-forming and radio-emitting regions.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17816
ER  -