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| Paper: |
Spectral Analyses of Wolf-Rayet Type Central Stars |
| Volume: |
469, 18th European White Dwarf Workshop (EUROWD12) |
| Page: |
303 |
| Authors: |
Todt, H.; Peña, M.; Hamann, W.-R.; Gräfener, G. |
| Abstract: |
A considerable fraction of the central stars of planetary nebulae
(CSPNe) are hydrogen-deficient. These stars are commonly considered as
the progenitors of H-deficient white dwarfs. As a rule, these CSPNe
exhibit a chemical composition of helium, carbon, and oxygen, most of
them showing Wolf-Rayet-like emission line spectra and are therefore
classified as of spectral type [WC]. Moreover, a few CSPNe of other
Wolf-Rayet spectral subtypes have been identified in the last years,
e.g. PB 8, which is of spectral type [WN/WC]. We performed spectral
analyses for a number of Wolf-Rayet type central stars with the help
of our Potsdam Wolf-Rayet (PoWR) model code for expanding atmospheres
to determine meaningful stellar parameters. The results of our
analyses are presented here in the context of stellar evolution and
white dwarf formation. We discuss the problems of a uniform
evolutionary channel for [WC] stars as well as constraints of the
formation of [WN/WC] subtype stars. |
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