Institut für Astronomie und Astrophysik

Abteilung Astronomie

Preprint H/98

Born-again AGB stars: Starting point of the H-deficient post-AGB evolutionary sequence?

K. Werner(1), S. Dreizler(1), T. Rauch(1), L. Koesterke(2), U. Heber(3)

(1)Institut für Astronomie und Astrophysik, Astronomie, Universität Tübingen, Waldhäuser Str. 64, D-72076 Tübingen, Germany
(2)Institut für Physik, Universität Potsdam, Germany
(3)Sternwarte Bamberg, Universität Erlangen-Nfürnberg, Germany

1999, Proc. IAU Symposium 191: Asymptotic Giant Branch Stars, eds. T. Le Bertre, A. Lebre, C. Waelkens, The ASP Conference Series, in press

Abstract. We discuss the origin of hot hydrogen-deficient post-AGB stars. Evidence is growing that the `born-again AGB star scenario' as a consequence of a late He shell flash cannot explain the diverse observations. Analyses of the stars and their associated planetary nebulae suggest that the H-deficiency is not formed during the second post-AGB phase but already while the star is still on the AGB. There are even hints that the H-deficiency can occur before the first departure from the AGB.

Key words: AGB Stars, White Dwarfs, Central Stars of Planetary Nebulae

Paper (83k gzip'ed Postscript including figures)

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Jürgen Barnstedt (barnstedt AT astro.uni-tuebingen.de) Last updated 17-Sep-1998