Nagasawa, DQ;
Marshall, JL;
Li, TS;
Hansen, TT;
Simon, JD;
Bernstein, RA;
Balbinot, E;
... Yanny, B; + view all
(2018)
Chemical Abundance Analysis of Three alpha-poor, Metal-poor Stars in the Ultrafaint Dwarf Galaxy Horologium I.
The Astrophysical Journal
, 852
(2)
, Article 99. 10.3847/1538-4357/aaa01d.
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Abstract
We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several α-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H] ~ −2.6 and are not α-enhanced ([α/Fe] ~ 0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility of a different mechanism for the enrichment of Hor I compared to other satellites. We discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud.
| Type: | Article |
|---|---|
| Title: | Chemical Abundance Analysis of Three alpha-poor, Metal-poor Stars in the Ultrafaint Dwarf Galaxy Horologium I |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4357/aaa01d |
| Publisher version: | http://doi.org/10.3847/1538-4357/aaa01d |
| Language: | English |
| Additional information: | © 2018. The American Astronomical Society. All rights reserved. This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Physical Sciences, Astronomy & Astrophysics, galaxies: abundances, galaxies: dwarf, stars: abundances, stars: chemically peculiar, LABORATORY TRANSITION-PROBABILITIES, R-PROCESS-RICH, HIGH-RESOLUTION SPECTROSCOPY, SPHEROIDAL GALAXY, OSCILLATOR-STRENGTHS, GALACTIC HALO, ECHELLE SPECTROGRAPH, DARK-MATTER, 1ST STARS, SUN |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1571430 |
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