Chemical abundances in bright giants of the globular cluster M62 (NGC 6266)

David Yong, Alan Alves-Brito, Gary Stewart Da Costa, Javier Alonso-Garcia, Amanda Irene Karakas, Marco Pignatari, Ian U Roederer, Wako Aoki, Cherie K Fishlock, Frank Grundahl, John Edward Norris

Research output: Contribution to journalArticleResearchpeer-review

30 Citations (Scopus)

Abstract

With the exception of Terzan 5, all the Galactic globular clusters that possess significant metallicity spreads, such as ω Cen and M22, are preferentially the more luminous clusters with extended horizontal branches. Here we present radial velocities and chemical abundances for seven bright giants in the globular cluster M62, a previously little-studied cluster. With MV = −9.18, M62 is the ninth most luminous Galactic globular cluster and has an extended horizontal branch. Within our sample, we find (i) no evidence for a dispersion in metallicity, [Fe/H], beyond the measurement uncertainties, (ii) star-to-star abundance variations for C, O, Na and Al with the usual correlations between these elements as seen in other globular clusters, and (iii) a global enrichment for the elements Zr, Ba and La at the level [X/Fe] ≃ +0.4 dex. For elements heavier than La, the abundance ratios are consistent with the scaled-solar r-process distribution. Below La, the abundances are anomalous when compared to the scaled-solar s-process or r-process distributions. For these elements, the abundance signature in M62 is in agreement with predictions of the s-process from fast-rotating massive stars, although the high [Rb/Y] ratio we measure may be a challenge to this scenario.
Original languageEnglish
Pages (from-to)2638-2650
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Volume439
Issue number3
DOIs
Publication statusPublished - 11 Apr 2014
Externally publishedYes

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