Observations of r- and s-process elements in Population II stars

Abstract

The framework for the interpretation of neutron-capture elements observed in Population II stars, established 20-25 years ago, is that these stars primarily exhibit r-process signatures, due to the inefficiency of the s-process at low metallicity. A view developed later that the r-process might be universal, which is to say that the same r-process element ratios would exist at high and low metallicity. However, observations of s-process abundances in low-metallicity environments, and departures from a universal r-process ratio for the lightest neutron-capture elements have required revisions to the framework. Observations indicating the need for and nature of these changes will be presented.

arXiv comment8 pages, 2 figures Conference paper: Nuclei in the Cosmos VII, Fuji-Yoshida, 8-12 July 2002

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