The Gaia-ESO Survey: the most metal-poor stars in the Galactic bulge

Titulo: 
The Gaia-ESO Survey: the most metal-poor stars in the Galactic bulge
Autores: 
Howes, LM; Asplund, M; Casey, AR; Keller, SC; Yong, D; Gilmore, G; Lind, K; Worley, C; Bessell, MS; Casagrande, L; Marino, AF; Nataf, DM; Owen, CI; Da Costa, GS; Schmidt, BP; Tisserand, P; Randich, S; Feltzing, S; Vallenari, A; Prieto, CA; Bensby, T; Flaccomio, E; Korn, AJ; Pancino, E; Recio-Blanco, A; Smiljanic, R; Bergemann, M; Costado, MT; Damiani, F; Heiter, U; Hill, V; Hourihane, A; Jofre, P; Lardo, C; de Laverny, P; Magrini, L; Maiorca, E; Masseron, T; Morbidelli, L; Sacco, GG; Minniti, D; Zoccali, M
Resumen: 
We present the first results of the EMBLA survey (Extremely Metal-poor BuLge stars with AAOmega), aimed at finding metal-poor stars in the Milky Way bulge, where the oldest stars should now preferentially reside. EMBLA utilizes SkyMapper photometry to pre-select metal-poor candidates, which are subsequently confirmed using AAOmega spectroscopy. We describe the discovery and analysis of four bulge giants with -2.72 <= [Fe/H] <= -2.48, the lowest metallicity bulge stars studied with high-resolution spectroscopy to date. Using FLAMES/UVES spectra through the Gaia-ESO Survey we have derived abundances of twelve elements. Given the uncertainties, we find a chemical similarity between these bulge stars and halo stars of the same metallicity, although the abundance scatter may be larger, with some of the stars showing unusual [alpha/Fe] ratios.
Autor principal: 
Howes, LM
Autor/es del IAA: 
Costado, M. T.
DOI: 
10.1093/mnras/stu1991
Revista: 
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Fecha de publicación: 
2014/12/21
Volumen: 
445
Issue: 
4
Páginas: 
4241-4246
Tipo de documento: 
Article
Palabras clave: 
stars: abundances; stars: Population II; Galaxy: bulge; Galaxy: evolution