The Gaia-ESO Survey: alpha-abundances of metal-poor stars

Research output: Contribution to journalArticle


We performed a detailed study of the ratio of low-alpha to high-alpha stars in the Galactic halo as observed by the Gaia-ESO Survey. Using a sample of 381 metal-poor stars from the second internal data release, we found that the value of this ratio did not show evidence of systematic trends as a function of metallicity, surface gravity, Galactic latitude, Galactic longitude, height above the Galactic plane, and Galactocentric radius. We conclude that the alpha(poor)/alpha(rich) value of 0.28 +/- 0.08 suggests that in the inner halo, the larger portion of stars were formed in a high star formation rate environment, and about 15% of the metal-poor stars originated from much lower star formation rate environments.


  • R. Jackson-Jones
  • P. Jofre
  • K. Hawkins
  • A. Hourihane
  • G. Gilmore
  • G. Kordopatis
  • C. Worley
  • S. Randich
  • A. Vallenari
  • A. Bragaglia
  • E. Flaccomio
  • A. J. Korn
  • A. Recio-Blanco
  • R. Smiljanic
  • M. T. Costado
  • U. Heiter
  • V. Hill
  • C. Lardo
  • P. de Laverny
  • G. Guiglion
  • S. Mikolaitis
  • S. Zaggia
  • G. Tautvaisiene
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology


  • stars: abundances, Galaxy: halo
Original languageEnglish
Article numberL5
JournalAstronomy & Astrophysics
Publication statusPublished - 2014
Publication categoryResearch

Related projects

Gerry Gilmore, Sofia Randich, Sofia Feltzing, Thomas Bensby, Louise Howes, Pieter Gruyters, Nils Ryde, Edita Stonkute & Gregory Ruchti


Project: ResearchInternational collaboration

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