Chemical abundances in the nucleus of the Sagittarius dwarf spheroidal galaxy
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Fecha
2017-09
Profesor/a Guía
Facultad/escuela
Idioma
en
Título de la revista
ISSN de la revista
Título del volumen
Editor
EDP Sciences
Nombre de Curso
Licencia CC
CC BY 4.0 DEED
Atribución 4.0 Internacional
Licencia CC
https://creativecommons.org/licenses/by/4.0/deed.es
Resumen
We present iron, magnesium, calcium, and titanium abundances for 235 stars in the central region of the Sagittarius dwarf spheroidal galaxy (within 9:00∼70 pc from the centre) from medium-resolution Keck/Deep Imaging Multi-Object Spectrograph spectra. All the considered stars belong to the massive globular cluster M 54 or to the central nucleus of the galaxy (Sgr, N). In particular we provide abundances for 109 stars with [Fe/H] ≥-1:0, more than doubling the available sample of spectroscopic metallicity and-elements abundance estimates for Sgr dSph stars in this metallicity regime.We find for the first time a metallicity gradient in the Sgr,N population, whose peak iron abundance goes from [Fe/H] =-0:38 for R ≤2:50 to [Fe/H] =-0:57 for 5:0 < R 9:0. On the other hand, the trends of [Mg/Fe], [Ca/Fe], and [Ti/Fe] with [Fe/H] are the same over the entire region explored by our study.We reproduce the observed chemical patterns of the Sagittarius dwarf spheroidal as a whole with a chemical evolution model which implies that a high mass progenitor (MDM = 6 1010 M) and a significant event of mass-stripping occurred a few Gyr ago, presumably starting at the first peri-Galactic passage after infall.
Notas
Indexación: Scopus
Palabras clave
Galaxies: Dwarf, Galaxies: Stellar content, Local Group, Stars: Abundances
Citación
Astronomy and Astrophysics Volume 6051 September 2017 Article number A46
DOI
10.1051/0004-6361/201730707