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

A. Recio-Blanco, A. Rojas-Arriagada, P. De Laverny, S. Mikolaitis, V. Hill, M. Zoccali, J. G. Fernández-Trincado, A. C. Robin, C. Babusiaux, G. Gilmore, S. Randich, E. Alfaro, C. Allende Prieto, A. Bragaglia, G. Carraro, P. Jofré, C. Lardo, L. Monaco, L. Morbidelli, S. Zaggia

Resultado de la investigación: Contribución a una revistaArtículo

17 Citas (Scopus)

Resumen

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.

Idioma originalInglés
Número de artículoL14
PublicaciónAstronomy and Astrophysics
Volumen602
DOI
EstadoPublicada - 1 jun 2017

Áreas temáticas de ASJC Scopus

  • Astronomía y astrofísica
  • Ciencias planetarias y espacial

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    Recio-Blanco, A., Rojas-Arriagada, A., De Laverny, P., Mikolaitis, S., Hill, V., Zoccali, M., Fernández-Trincado, J. G., Robin, A. C., Babusiaux, C., Gilmore, G., Randich, S., Alfaro, E., Allende Prieto, C., Bragaglia, A., Carraro, G., Jofré, P., Lardo, C., Monaco, L., Morbidelli, L., & Zaggia, S. (2017). The Gaia-ESO Survey: Low-α element stars in the Galactic bulge. Astronomy and Astrophysics, 602, [L14]. https://doi.org/10.1051/0004-6361/201630220