2014MNRAS.443..658D -
Mon. Not. R. Astron. Soc., 443, 658-663 (2014/September-1)
The α-element knee of the Sagittarius stream.
DE BOER T.J.L., BELOKUROV V., BEERS T.C. and LEE Y.S.
Abstract (from CDS):
We employ abundances from the Sloan Digital Sky Survey (SDSS) and the Sloan Extension for Galactic Understanding and Exploration (SEGUE) to study the α-element distribution of the stellar members of the Sagittarius stream. To test the reliability of SDSS/SEGUE abundances for the study of Sagittarius, we select high-likelihood samples tracing the different components of the Milky Way, and recover known literature α-element distributions. Using selection criteria based on the spatial position, radial velocity, distance and colours of individual stars, we obtain a robust sample of Sagittarius-stream stars. The α-element distribution of the Sagittarius stream forms a narrow sequence at intermediate metallicities with a clear turn-down, consistent with the presence of an α-element `knee'. This is the first time that the α-element knee of the Sagittarius dwarf galaxy has been detected. Fitting a toy model to our data, we determine that the α-knee in Sagittarius takes place at [Fe/H]=-1.27±0.05, only slightly less metal-poor than the knee in the Milky Way. This indicates that a small number of Sagittarius-like galaxies could have contributed significantly to the build-up of the Milky Way's stellar halo system at ancient times.
Abstract Copyright:
© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2014)
Journal keyword(s):
galaxies: evolution - galaxies: formation - galaxies: individual: Sagittarius - Local Group - galaxies: stellar content
Simbad objects:
9
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