The Gaia-ESO Survey: Low-α element stars in the Galactic bulge - Observatoire de la Cote d'Azur Accéder directement au contenu
Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2017

The Gaia-ESO Survey: Low-α element stars in the Galactic bulge

P. de Laverny
S. Mikolaitis
  • Fonction : Auteur
V. Hill
M. Zoccali
G. Gilmore
  • Fonction : Auteur
S. Randich
  • Fonction : Auteur
E. Alfaro
  • Fonction : Auteur
C. Allende Prieto
A. Bragaglia
G. Carraro
  • Fonction : Auteur
P. Jofre
  • Fonction : Auteur
C. Lardo
  • Fonction : Auteur
L. Monaco
  • Fonction : Auteur
L. Morbidelli
  • Fonction : Auteur
S. Zaggia
  • Fonction : Auteur

Résumé

We take advantage of the Gaia-ESO Survey iDR4 bulge data to search for abundance anomalies that could shed light on the composite nature of the Milky Way bulge. The α-element (Mg, Si, and whenever available, Ca) abundances, and their trends with Fe abundances have been analysed for a total of 776 bulge stars. In addition, the aluminum abundances and their ratio to Fe and Mg have also been examined. Our analysis reveals the existence of low-α element abundance stars with respect to the standard bulge sequence in the [α/ Fe] versus [Fe/H] plane. Eighteen objects present deviations in [α/ Fe] ranging from 2.1 to 5.3σ with respect to the median standard value. Those stars do not show Mg-Al anti-correlation patterns. Incidentally, this sign of the existence of multiple stellar populations is reported firmly for the first time for the bulge globular cluster NGC 6522. The identified low-α abundance stars have chemical patterns that are compatible with those of the thin disc. Their link with massive dwarf galaxies accretion seems unlikely, as larger deviations in α abundance and Al would be expected. The vision of a bulge composite nature and a complex formation process is reinforced by our results. The approach used, which is a multi-method and model-driven analysis of high resolution data, seems crucial to reveal this complexity.
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Dates et versions

hal-01593668 , version 1 (16-01-2021)

Identifiants

Citer

A. Recio-Blanco, A. Rojas-Arriagada, P. de Laverny, S. Mikolaitis, V. Hill, et al.. The Gaia-ESO Survey: Low-α element stars in the Galactic bulge. Astronomy and Astrophysics - A&A, 2017, 602, pp.L14. ⟨10.1051/0004-6361/201630220⟩. ⟨hal-01593668⟩
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