Chemical Abundance Analysis of Three alpha-poor, Metal-poor Stars in the Ultrafaint Dwarf Galaxy Horologium I Academic Article uri icon


  • 2018. The American Astronomical Society. All rights reserved.. 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 -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 -enhanced ([/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.

published proceedings


altmetric score

  • 28.75

author list (cited authors)

  • Nagasawa, D. Q., Marshall, J. L., Li, T. S., Hansen, T. T., Simon, J. D., Bernstein, R. A., ... Yanny, B.

citation count

  • 25

complete list of authors

  • Nagasawa, DQ||Marshall, JL||Li, TS||Hansen, TT||Simon, JD||Bernstein, RA||Balbinot, E||Drlica-Wagner, A||Pace, AB||Strigari, LE||Pellegrino, CM||DePoy, DL||Suntzeff, NB||Bechtol, K||Walker, AR||Abbott, TMC||Abdalla, FB||Allam, S||Annis, J||Benoit-Lévy, A||Bertin, E||Brooks, D||Rosell, A Carnero||Kind, M Carrasco||Carretero, J||Cunha, CE||D’Andrea, CB||da Costa, LN||Davis, C||Desai, S||Doel, P||Eifler, TF||Flaugher, B||Fosalba, P||Frieman, J||García-Bellido, J||Gaztanaga, E||Gerdes, DW||Gruen, D||Gruendl, RA||Gschwend, J||Gutierrez, G||Hartley, WG||Honscheid, K||James, DJ||Jeltema, T||Krause, E||Kuehn, K||Kuhlmann, S||Kuropatkin, N||March, M||Miquel, R||Nord, B||Roodman, A||Sanchez, E||Santiago, B||Scarpine, V||Schindler, R||Schubnell, M||Sevilla-Noarbe, I||Smith, M||Smith, RC||Soares-Santos, M||Sobreira, F||Suchyta, E||Tarle, G||Thomas, D||Tucker, DL||Wechsler, RH||Wolf, RC||Yanny, B

publication date

  • January 2018