Chemical abundances in a high-velocity RR Lyrae star near the bulge

Hansen, C. J. and Rich, R. M. and Koch, A. and Xu, S. and Kunder, A. and Ludwig, H.-G. (2016) Chemical abundances in a high-velocity RR Lyrae star near the bulge. Astronomy and Astrophysics, 590. ISSN 0004-6361

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Abstract

Low-mass variable high-velocity stars are interesting study cases for many aspects of Galactic structure and evolution. Until recently, the only known high- or hyper-velocity stars were young stars thought to originate from the Galactic center. Wide-area surveys such as APOGEE and BRAVA have found several low-mass stars in the bulge with Galactic rest-frame velocities higher than 350 km s-1. In this study we present the first abundance analysis of a low-mass RR Lyrae star that is located close to the Galactic bulge, with a space motion of ~–400 km s-1. Using medium-resolution spectra, we derived abundances (including upper limits) of 11 elements. These allowed us to chemically tag the star and discuss its origin, although our derived abundances and metallicity, at [Fe/H] =−0.9 dex, do not point toward one unambiguous answer. Based on the chemical tagging, we cannot exclude that it originated in the bulge. However, its retrograde orbit and the derived abundances combined suggest that the star was accelerated from the outskirts of the inner (or even outer) halo during many-body interactions. Other possible origins include the bulge itself, or the star might have been stripped from a stellar cluster or the Sagittarius dwarf galaxy when it merged with the Milky Way.

Item Type: Journal Article
Journal or Publication Title: Astronomy and Astrophysics
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/1900/1912
Subjects:
Departments: Faculty of Science and Technology > Physics
ID Code: 79549
Deposited By: ep_importer_pure
Deposited On: 18 May 2016 14:18
Refereed?: Yes
Published?: Published
Last Modified: 15 Oct 2019 03:41
URI: https://eprints.lancs.ac.uk/id/eprint/79549

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