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IRAS08281-4850 and IRAS14325-6428: two A-type post-AGB stars with s-process enrichment by Reyniers, M.; Van de Steene, G. C.; van Hoof, P. A. M.; Van Winckel, H. is a scholarly article available to read on EtoBox.

What is IRAS08281-4850 and IRAS14325-6428: two A-type post-AGB stars with s-process enrichment about?

One of the puzzling findings in the study of the chemical evolution of (post-)AGB stars is why very similar stars (in terms of metallicity, spectral type, infrared properties, etc...) show a very different photospheric composition. We aim at extending the still limited sample of s-process enriched post-AGB stars, in order to obtain a statistically large enough sample that allows us to formulate conclusions concerning the 3rd dredge-up occurrence. We selected two post-AGB stars on the basis of IR colours indicative of a past history of heavy mass loss: IRAS08281-4850 and IRAS14325-6428. They are cool sources in the locus of the Planetary Nebulae (PNe) in the IRAS colour-colour diagram. Abundances of both objects were derived for the first time on the basis of high-quality UVES and EMMI spectra, using a critically compiled line list with accurate log(gf) values, together with the latest Kurucz model atmospheres. Both objects have very similar spectroscopically defined effective temperatures of 7750-8000K. They are strongly carbon and s-process enriched, with a C/O ratio of 1.9 and 1.6, and an [ls/Fe] of +1.7 and +1.2, for IRAS08281 and IRAS14325 resp. Moreover, the spectral energy di

Author

Reyniers, M.; Van de Steene, G. C.; van Hoof, P. A. M.; Van Winckel, H.

Published

2007

Language

EN