期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 509, 期 3, 页码 4637-4652出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stab3364
关键词
stars: abundances; stars: individual: J01020100-7122208; Galaxy: abundances; Galaxy: halo
资金
- ECOS-Anid grant [140089, 180049]
- FONDECYT [11170174, 1200703]
- TDA/Scialog grant (2019-2021) - Heising-Simons Foundation
- Wootton Center for Astrophysical Plasma Properties under the United States Department of Energy [DE-NA0003843]
- National Science Foundation [AST-1907417]
- ANID through the Fondecyt regular grant [1191038]
- ANID through the Millennium Science Initiative [ICN12 009]
- Australian Astronomical Observatory [A/2013B/13, A/2014A/25, A/2015A/19, A2017A/18, A2018A/18, A2019A/1, A2019A/15, A/2015B/19, A/2016A/22, A/2016B/10, A/2017B/16, A/2018B/15, A/2015A/3, A/2015B/1, A/2016A/22 A/2016B/12 A/2017A/14]
- TDA/Scialog (2018-2020) grant - Research Corporation
Our study reveals that J01020100-7122208 is a star with a retrograde and highly-eccentric orbit, likely accreted by the Milky Way in the distant past. Its mass and age suggest it is probably an evolved blue straggler.
J01020100-7122208 is a star whose origin and nature still challenges us. It was first believed to be a yellow supergiant ejected from the Small Magellanic Cloud, hut it was more recently claimed to be a red giant accelerated by the Milky Way's central black hole. In order to unveil its nature, we analysed photometric, astrometric, and high-resolution spectroscopic observations to estimate the orbit, age, and 16 elemental abundances. Our results show that this star has a retrograde and highly-eccentric orbit, e = 0.914(-0.020)(+0.016). Correspondingly, it likely crossed the Galactic disc at 550 pc from the Galactic Centre. We obtained a spectroscopic mass and age of 1.09 +/- 0.10 M-circle dot and 4.51 +/- 1.44 Gyr, respectively. Its chemical composition is similar to the abundance of other retrograde halo stars. We found that the star is enriched in europium, having (Eu/Fe] = 0.93 +/- 0.24, and is more metal-poor than reported in the literature, with [Fe/H] = -1.30 +/- 0.10. This information was used to conclude that J01020100-7122208 is likely not a star ejected from the central black of the Milky Way or from the Small Magellanic Cloud. Instead, we propose that it is simply a halo star that was likely accreted by the Milky Way in the distant past, but its mass and age suggest it is probably an evolved blue straggler.
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