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

Yong, David; Alves Brito, Alan; Da Costa, Gary S.; Alonso-García, Javier; Karakas, Amanda I.; Pignatari, Marco; Roederer, Ian U.; Aoki, Wako; Fishlock, Cherie K.; Grundahl, Frank; Norris, John E.

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.

Citation

Yong, D., Alves Brito, A., Da Costa, G. S., Alonso-García, J., Karakas, A. I., Pignatari, M., Roederer, I. U., Aoki, W., Fishlock, C. K., Grundahl, F., & Norris, J. E. (2014). Chemical abundances in bright giants of the globular cluster M62 (NGC 6266). Monthly notices of the Royal Astronomical Society, 439(3), 2638-2650. https://doi.org/10.1093/mnras/stu118

• Journal Article Type: Article
• Acceptance Date: Jan 15, 2014
• Online Publication Date: Feb 15, 2014
• Publication Date: Apr 11, 2014
• Deposit Date: Apr 15, 2016
• Publicly Available Date: Apr 15, 2016
• Journal: Monthly notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 439
• Issue: 3
• Pages: 2638-2650
• DOI: https://doi.org/10.1093/mnras/stu118
• Keywords: Stars : abundances, Galaxy : abundances, Globular clusters : individual : NGC 6266
• Public URL: https://hull-repository.worktribe.com/output/436155
• Publisher URL: http://mnras.oxfordjournals.org/content/439/3/2638.full#fn-12
• Additional Information: This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
• Contract Date: Apr 15, 2016