Heavy‐Element Abundances in Giant Stars in 47 Tucanae

Abstract

This research forms part of an investigation into heavy-element abundances in asymptotic giant branch (AGB) stars in various stellar environments. Seven giant stars in the southern globular cluster 47 Tuc have been observed using the Anglo-Australian Telescope. Abundances for five s-and r-process elements have been determined: the light s-process elements Y and Zr, the heavy s-process elements La and Nd, and the r-process element Eu. Mean enhance-ments in the light s-process elements, [ls/Fe], of $+0.6 dex and heavy s-process elements, [hs/Fe], of $+0.3 dex were determined for all the giant stars. There was no statistically significant difference between the abundances determined for the red giant branch (RGB) and AGB stars in this study. The results for the RGB stars differ from those obtained by a number of previous studies. However, because of the similar abundance results obtained for the AGB and RGB stars in this study, we believe this provides evidence for previous enrichment of the material from which these stars formed. Subject headingg s: globular clusters: general — globular clusters: individual (NGC 104, 47 Tucanae) — nuclear reactions, nucleosynthesis, abundances — stars: abundances — stars: AGB and post-AGB