Institut für Astronomie und Astrophysik
Abteilung AstronomieSand 1, D-72076 Tübingen, Germany
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Klaus Werner (1), Falk Herwig (2)
(2) Los Alamos National Laboratory
To be published in: PASP
Abstract. We review the observed properties of extremely hot hydrogen-deficient post-AGB stars of spectral type [WC] and PG1159. Their H-deficiency is probably caused by a (very) late helium-shell flash or a AGB final thermal pulse, laying bare interior stellar regions which are usually kept hidden below the hydrogen envelope. Thus, the photospheric element abundances of these stars allow to draw conclusions about details of nuclear burning and mixing processes in the precursor AGB stars. We summarize the state-of-the-art of stellar evolution models which simulate AGB evolution and the occurrence of a late He-shell flash. We compare predicted element abundances to those determined by quantitative spectral analyses performed with advanced non-LTE model atmospheres. A good qualitative and quantitative agreement is found. Future work can contribute to an even more complete picture of the nuclear processes in AGB stars.
Preprint (1,30 Mb PDF file including figures)
Astrophysics (astro-ph): astro-ph/0512320
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Last modified 30 Jan 2013