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Chemical trends in the Galactic halo from APOGEE data

Fernandez-Alvar, E; Carigi, L; Prieto, CA; Hayden, MR; Beers, TC; Fernandez-Trincado, JG; Meza, A; Schultheis, M; Santiago, BX; Queiroz, AB; Anders, F; da Costa, LN; Chiappini, C (OXFORD UNIV PRESS, 2016-11)

The galaxy formation process in the A cold dark matter scenario can be constrained from the analysis of stars in the Milky Way's halo system. We examine the variation of chemical abundances in distant halo stars observed ...

Disentangling the Galactic Halo with APOGEE. I. Chemical and Kinematical Investigation of Distinct Metal-poor Populations

Hayes, C.R.; Majewski, S.R.; Shetrone, M.; Fernández-Alvar, E.; Prieto, C.A.; Schuster, W.J.; Carigi, L.; Cunha, K.; Smith, V.V.; Sobeck, J.; Almeida, A.; Beers, T.C.; Carrera, R.; Fernández-Trincado, J.G.; García-Hernández, D.A.; Geisler, D.; Lane, R.R.; Lucatello, S.; Matthews, A.M.; Minniti, D.; Nitschelm, C.; Tang, B.; Tissera, P.B.; Zamora, O. (Institute of Physics Publishing, 2018)

We find two chemically distinct populations separated relatively cleanly in the [Fe/H]-[Mg/Fe] plane, but also distinguished in other chemical planes, among metal-poor stars (primarily with metallicities [Fe H] < -0.9) ...

Disentangling the Galactic Halo with APOGEE. II. Chemical and Star Formation Histories for the Two Distinct Populations

Fernández-Alvar, E.; Carigi, L.; Schuster, W.J.; Hayes, C.R.; Ávila-Vergara, N.; Majewski, S.R.; Allende Prieto, C.; Beers, T.C.; Sánchez, S.F.; Zamora, O.; García-Hernández, D.A.; Tang, B.; Fernández-Trincado, J.G.; Tissera, P.; Geisler, D.; Villanova, S. (Institute of Physics Publishing, 2018)

The formation processes that led to the current Galactic stellar halo are still under debate. Previous studies have provided evidence for different stellar populations in terms of elemental abundances and kinematics, ...

TOPoS: IV. Chemical abundances from high-resolution observations of seven extremely metal-poor stars

Bonifacio, P.; Caffau, E.; Spite, M.; Spite, F.; Sbordone, L.; Monaco, L.; François, P.; Plez, B.; Molaro, P.; Gallagher, A.J.; Cayrel, R.; Christlieb, N.; Klessen, R.S.; Koch, A.; Ludwig, H.-G.; Steffen, M.; Zaggia, S.; Abate, C. (EDP Sciences, 2018-04)

Context. Extremely metal-poor (EMP) stars provide us with indirect information on the first generations of massive stars. The TOPoS survey has been designed to increase the census of these stars and to provide a chemical ...

Investigation of a sample of carbon-enhanced metal-poor stars observed with FORS and GMOS

Caffau, E.; Gallagher, A.J.; Bonifacio, P.; Spite, M.; Duffau, S.; Spite, F.; Monaco, L.; Sbordone, L. (EDP Sciences, 2018-06)

Aims. Carbon-enhanced metal-poor (CEMP) stars represent a sizeable fraction of all known metal-poor stars in the Galaxy. Their formation and composition remains a significant topic of investigation within the stellar ...

Ages and Heavy Element Abundances from Very Metal-poor Stars in the Sagittarius Dwarf Galaxy

Hansen, C.J.; El-Souri, M.; Monaco, L.; Villanova, S.; Bonifacio, P.; Caffau, E.; Sbordone, L. (Institute of Physics Publishing, 2018-03)

Sagittarius (Sgr) is a massive disrupted dwarf spheroidal galaxy in the Milky Way halo that has undergone several stripping events. Previous chemical studies were restricted mainly to a few, metal-rich ([Fe/H] ) stars that ...