Choplin, A, Hirschi, R, Meynet, G and Ekström, S (2017) Are some CEMP-s stars the daughters of spinstars? Astronomy and Astrophysics, 607. L3 -L3. ISSN 1432-0746

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Carbon-enhanced metal-poor (CEMP)-s stars are long-lived low-mass stars with a very low iron content as well as overabundances of carbon and s-elements. Their peculiar chemical pattern is often explained by pollution from an asymptotic giant branch (AGB) star companion. Recent observations have shown that most CEMP-s stars are in binary systems, providing support to the AGB companion scenario. A few CEMP-s stars, however, appear to be single. We inspect four apparently single CEMP-s stars and discuss the possibility that they formed from the ejecta of a previous-generation massive star, referred to as the “source” star. In order to investigate this scenario, we computed low-metallicity massive-star models with and without rotation and including complete s-process nucleosynthesis. We find that non-rotating source stars cannot explain the observed abundance of any of the four CEMP-s stars. Three out of the four CEMP-s stars can be explained by a 25M⊙ source star with vini ~ 500 km s-1 (spinstar). The fourth CEMP-s star has a high Pb abundance that cannot be explained by any of the models we computed. Since spinstars and AGB predict different ranges of [O/Fe] and [ls/hs], these ratios could be an interesting way to further test these two scenarios. nuclear reactions, nucleosynthesis, abundances / stars: interiors / stars: chemically peculiar / stars: abundances / stars: massive

Item Type: Article
Additional Information: © 2017 ESO. This is the final published version of the article (version of record). It first appeared online via EDP Sciences at - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: nuclear reactions, nucleosynthesis, abundances, stars, interiors, chemically peculiar, massive
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Symplectic
Date Deposited: 17 Nov 2017 16:24
Last Modified: 17 Nov 2017 16:26

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