Discovery of a new stellar subpopulation residing in the (Inner) stellar halo of the milky way
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Archivos
Fecha
2019-11
Profesor/a Guía
Facultad/escuela
Idioma
en
Título de la revista
ISSN de la revista
Título del volumen
Editor
Institute of Physics Publishing
Nombre de Curso
Licencia CC
Atribution 4.0 International (CC BY 4.0)
Licencia CC
https://creativecommons.org/licenses/by/4.0/deed.es
Resumen
We report the discovery of a unique collection of metal-poor giant stars that exhibit anomalously high levels of 28Si,
clearly above typical Galactic levels. Our sample spans a narrow range of metallicities, peaking at −1.07 ± 0.06,
and exhibits abundance ratios of [Si, Al/Fe] that are as extreme as those observed in Galactic globular clusters
(GCs), and Mg is slightly less overabundant. In almost all the sources we used, the elemental abundances were
redetermined from high-resolution spectra, which were reanalyzed assuming LTE. Thus, we compiled the main
element families, namely, the light elements (C, N), α-elements (O, Mg, Si), iron-peak element (Fe), s-process
elements (Ce, Nd), and the light odd-Z element (Al). We also provide dynamical evidence that most of these stars
lie on tight (inner) halo-like and retrograde orbits passing through the bulge. Such kinds of objects have been found
in present-day halo GCs, providing the clearest chemical signature of past accretion events in the (inner) stellar
halo of the galaxy, possibly formed as the result of dissolved halo GCs. Their chemical composition is, in general,
similar to that of typical GC populations, although several differences exist.
Notas
Indexación: Scopus.
Palabras clave
Chemically Peculiar Stars (226), Stellar Dynamics (1596), Galaxy Stellar Content (1608), Galaxy Stellar Halos (598), Silicon Stars (1459), High Resolution Spectroscopy (2096), Stellar Abundances, Stellar Kinematics (1608)
Citación
Astrophysical Journal Letters Volume 886, Issue 120 November 2019 Article number L8
DOI
DOI: 10.3847/2041-8213/ab5286