2014/06/12 by Thomas de Boer, T. J. L. de Boer, Vasily Belokurov +5 · 63 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Dwarf galaxy #Dwarf spheroidal galaxy #Galactic halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Interacting galaxy #Milky Way #Physics #Sagittarius #Sagittarius A* #Stars #Stellar kinematics #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stu1176
published in Monthly Notices of the Royal Astronomical Society 443(1), 658-663 (Oxford University Press) · 6 pages, 3 figures
arxiv created 2014/06/12 · openalex publication_date 2014/07/14 · arxiv updated 2015/06/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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.