J01020100-7122208: an accreted evolved blue straggler that was not ejected from a supermassive black hole

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.