Are some CEMP-s stars the daughters of spinstars? [SSA]

http://arxiv.org/abs/1710.05564


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 a AGB star companion. Recent observations have shown that most of the CEMP-s stars are in a binary system, 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 $25$ $M_{\odot}$ source star with $v_{\rm ini} \sim 500$ 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.

Read this paper on arXiv…

A. Choplin, R. Hirschi, G. Meynet, et. al.
Tue, 17 Oct 17
41/163

Comments: 4 pages, accepted for publication in A&A