This work presents a new detection of H2absorption arising in a high-velocity cloud associated with either the Milky Way or the Large Magellanic Cloud (LMC). The absorber was found in an archival Far Ultraviolet Spectroscopic Explorer spectrum of the LMC star Sk-70°32. This is the fifth well-characterized H2absorber to be found in the Milky Way’s halo and the second such absorber outside the Magellanic Stream and Bridge. The absorber has a local standard of rest central velocity of +140 km s−1and a H2column density of 1017.5cm−2. It is most likely part of a cool and relatively dense inclusion (
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, $e=0.914_{-0.020}^{+0.016}$. Correspondingly, it likely crossed the Galactic disc at 550 pc from the Galactic Centre. We obtained a spectroscopic mass and age of $1.09\pm 0.10\, {\rm M}_\odot$ 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 more »
- Award ID(s):
- 1907417
- Publication Date:
- NSF-PAR ID:
- 10381816
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 509
- Issue:
- 3
- Page Range or eLocation-ID:
- p. 4637-4652
- ISSN:
- 0035-8711
- Publisher:
- Oxford University Press
- Sponsoring Org:
- National Science Foundation
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