Aluminum abundances of multiple stellar generations in the globular cluster NGC 1851

Elisa Carretta, V. D'Orazi, Raffaele G. Gratton, Sara Lucatello

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Abstract

We studied the distribution of aluminum abundances among red giants in the peculiar globular cluster NGC 1851. Aluminum abundances were derived from the strong doublet Al i 8772-8773 Ãmeasured on intermediate-resolution FLAMES spectra of 50 cluster stars acquired under the Gaia-ESO public survey. We coupled these abundances with previously derived abundances of O, Na, and Mg to fully characterize the interplay of the NeNa and MgAl cycles of H-burning at high temperature in the early stellar generation in NGC 1851. The stars in our sample show well-defined correlations between Al, Na and Si; Al is anticorrelated with O and Mg. The average value of the [Al/Fe] ratio steadily increases from the first generation stars to the second generation populations with intermediate and extremely modified composition. We confirm on a larger database the results recently obtained by us: the pattern of abundances of proton-capture elements implies a moderate production of Al in NGC 1851. We find evidence of a statistically significant positive correlation between Al and Ba abundances in the more metal-rich component of red giants in NGC 1851.

Original languageEnglish
Article numberA117
JournalAstronomy & Astrophysics
Volume543
DOIs
Publication statusPublished - 2012
Externally publishedYes

Keywords

  • Globular clusters: general
  • Globular clusters: individual: NGC 1851
  • Stars: abundances
  • Stars: atmospheres
  • Stars: Population II

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