Issue |
A&A
Volume 450, Number 2, May I 2006
|
|
---|---|---|
Page(s) | 701 - 714 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20053553 | |
Published online | 10 April 2006 |
Post-AGB stars as testbeds of nucleosynthesis in AGB stars
1
LUTH, Observatoire de Meudon, 5 Place Jules Janssen, 92195 Meudon Cedex, France e-mail: grazyna.stasinska@obspm.fr
2
N. Copernicus Astronomical Center, Rabiańska 8, 87-100 Toruń, 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 , 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 (
); 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
© ESO, 2006
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