The Gaia-ESO Survey: Detailed abundances in the metal-poor globular cluster NGC 4372

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Abstract

We present the abundance analysis for a sample of 7 red giant branch stars in the metal-poor globular cluster NGC 4372 based on UVES spectra acquired as part of the Gaia-ESO Survey. This is the first extensive study of this cluster from high-resolution spectroscopy. We derive abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, Fe, Cr, Ni, Y, Ba, and La. We find a metallicity of [Fe/H] = -2.19 +/- 0.03 and find no evidence of any metallicity spread. This metallicity makes NGC 4372 one of the most metal-poor Galactic globular clusters. We also find an a-enhancement typical of halo globular clusters at this metallicity. Significant spreads are observed in the abundances of light elements. In particular, we find a Na-O anticorrelation. Abundances of O are relatively high compared with other globular clusters. This could indicate that NGC 4372 was formed in an environment with high O for its metallicity. A Mg-Al spread is also present that spans a range of more than 0.5 dex in Al abundances. Na is correlated with Al and Mg abundances at a lower significance level. This pattern suggests that the Mg-Al burning cycle is active. This behavior can also be seen in giant stars of other massive, metal-poor clusters. A relation between light and heavy s-process elements has been identified.

Details

Authors
  • I. San Roman
  • C. Munoz
  • D. Geisler
  • S. Villanova
  • N. Kacharov
  • A. Koch
  • G. Carraro
  • G. Tautvaisiene
  • A. Vallenari
  • E. J. Alfaro
  • E. Flaccomio
  • P. Francois
  • A. J. Korn
  • E. Pancino
  • A. Recio-Blanco
  • R. Smiljanic
  • M. Bergemann
  • M. T. Costado
  • F. Damiani
  • U. Heiter
  • A. Hourihane
  • P. Jofre
  • C. Lardo
  • P. de Laverny
  • T. Masseron
  • L. Morbidelli
  • L. Sbordone
  • S. G. Sousa
  • C. C. Worley
  • S. Zaggia
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology

Keywords

  • globular clusters: individual: NGC 4372, stars: abundances
Original languageEnglish
Article numberA6
JournalAstronomy & Astrophysics
Volume579
Publication statusPublished - 2015
Publication categoryResearch
Peer-reviewedYes