J01020100−7122208: an accreted evolved blue straggler that was not ejected from a supermassive black hole
J01020100−7122208: an accreted evolved blue straggler that was not ejected from a supermassive black hole
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J01020100–7122208：一个吸积进化的蓝色离散粒子，不是从超大质量黑洞中喷射出来的
DOI：
10.1093/mnras/stab3364
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发表时间：
2021
影响因子：
4.8
通讯作者：
Hawkins, Keith
中科院分区：
文献类型：
--
作者：
De Brito Silva, Danielle;Jofré, Paula;Bourbert, Douglas;Koposov, Sergey E.;Prieto, Jose L.;Hawkins, Keith
J 01020100 - 7122208是一颗星星，它的起源和性质仍然挑战着我们。它最初被认为是一颗从小麦哲伦星云喷射出来的黄色超巨星，但最近被认为是一颗被银河系中央黑洞加速的红巨星。为了揭示它的性质，我们分析了光度，天体测量和高分辨率光谱观测，以估计轨道，年龄和16种元素丰度。我们的结果表明，这颗星星有一个逆行和高偏心率的轨道。相应地，它可能在距离银河系中心550 pc处穿过银河系圆盘。测得其光谱质量和年龄分别为4.51 ± 1.44 Gyr.它的化学成分与其他逆行晕星的丰度相似。我们发现这颗星星富含铕，[Eu/Fe] = 0.93 ± 0.24，比文献报道的[Fe/H] = −1.30 ± 0.10更贫金属。这些信息被用来推断J 01020100 −7122208可能不是从银河系中央黑洞或小麦哲伦星云中喷射出来的星星。相反，我们认为它只是一颗晕星星，可能在遥远的过去被银河系吸积，但它的质量和年龄表明它可能是一颗进化的蓝离散星。
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, but 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,. Correspondingly, it likely crossed the Galactic disc at 550 pc from the Galactic Centre. We obtained a spectroscopic mass and age ofand 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.