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Preprint 16a/07

Elemental Abundances in PG1159 Stars

K. Werner (1), T. Rauch (1), E. Reiff (1), J.W. Kruk (2)

(1) Institute for Astronomy and Astrophysic, Kepler Center for Astro and Particle Physics, Eberhard Karls University, Tübingen, Germany
(2) Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA

To be published in: Proceedings of "Hydrogen-Deficient Stars" conference, held in Tübingen, Germany, Sept. 17-21, 2007.

Abstract. The hydrogen-deficiency in extremely hot post-AGB stars of spectral class PG1159 is probably caused by a (very) late helium-shell flash or a AGB final thermal pulse that consumes the hydrogen envelope, exposing the usually-hidden intershell region. Thus, the photospheric elemental abundances of these stars allow to draw conclusions about details of nuclear burning and mixing processes in the precursor AGB stars. We compare predicted elemental abundances to those determined by quantitative spectral analyses performed with advanced non-LTE model atmospheres. A good qualitative and quantitative agreement is found for many species (He, C, N, O, Ne, F, Si, Ar) but discrepancies for others (P, S, Fe) point at shortcomings in stellar evolution models for AGB stars. PG1159 stars appear to be the direct progeny of [WC] stars.
 

Preprint (814 kb PDF file including figures)
Astrophysics (astro-ph): 0710.4506

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