EDP Sciences
Free access
Issue A&A
Volume 450, Number 2, May I 2006
Page(s) 701 - 714
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20053553

A&A 450, 701-714 (2006)
DOI: 10.1051/0004-6361:20053553

Post-AGB stars as testbeds of nucleosynthesis in AGB stars

G. Stasinska1, R. Szczerba2, M. Schmidt2 and N. Siódmiak2

1  LUTH, Observatoire de Meudon, 5 Place Jules Janssen, 92195 Meudon Cedex, France
    e-mail: grazyna.stasinska@obspm.fr
2  N. Copernicus Astronomical Center, Rabianska 8, 87-100 Torun, Poland

(Received 2 June 2005 / Accepted 30 December 2005 )

We construct a data base of 125 post-AGB objects (including R CrB and extreme helium stars) with published photospheric parameters (effective temperature and gravity) and chemical composition. We estimate the masses of the post-AGB stars by comparing their position in the (log $T_{\rm {eff}}$, log g) plane with theoretical evolutionary tracks of different masses. We construct various diagrams, with the aim of finding clues to AGB nucleosynthesis. This is the first time that a large sample of post-AGB stars has been used in a systematic way for such a purpose and we argue that, in several respects, post-AGB stars should be more powerful than planetary nebulae to test AGB nucleosynthesis. Our main findings are that: the vast majority of objects which do not show evidence of N production from primary C have a low stellar mass ( $M_{\star} < 0.56~M_{\odot}$); there is no evidence that objects which did not experience 3rd dredge-up have a different stellar mass distribution than objects that did; there is clear evidence that 3rd dredge-up is more efficient at low metallicity. The sample of known post-AGB stars is likely to increase significantly in the near future thanks to the ASTRO-F and follow-up observations, making these objects even more promising as testbeds for AGB nucleosynthesis.

Key words: stars: AGB and post AGB -- stars: abundances -- stars: evolution -- nuclear reactions, nucleosynthesis, abundances

SIMBAD Objects

© ESO 2006

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Editor-in-Chief: T. Forveille
Letters Editor-in-Chief: J. Alves
Managing Editor: N. Aghanim

ISSN: 0004-6361 ; e-ISSN: 1432-0746
Frequency: 12 volumes per year
Published by: EDP Sciences

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