An r-process Enhanced Star in the Dwarf Galaxy Tucana III

T. T. Hansen, J. D. Simon, J. L. Marshall, T. S. Li, D. Carollo, D. L. Depoy, D. Q. Nagasawa, R. A. Bernstein, A. Drlica-Wagner, F. B. Abdalla, S. Allam, J. Annis, K. Bechtol, A. Benoit-Lévy, D. Brooks, E. Buckley-Geer, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, C. E. CunhaL. N.Da Costa, S. Desai, T. F. Eifler, A. Fausti Neto, B. Flaugher, J. Frieman, J. García-Bellido, E. Gaztanaga, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, D. J. James, E. Krause, K. Kuehn, N. Kuropatkin, O. Lahav, R. Miquel, A. A. Plazas, A. K. Romer, E. Sanchez, B. Santiago, V. Scarpine, R. C. Smith, M. Soares-Santos, F. Sobreira, E. Suchyta, M. E.C. Swanson, G. Tarle, A. R. Walker

Research output: Contribution to journalArticle

Abstract

Chemically peculiar stars in dwarf galaxies provide a window for exploring the birth environment of stars with varying chemical enrichment. We present a chemical abundance analysis of the brightest star in the newly discovered ultra-faint dwarf galaxy candidate Tucana III. Because it is particularly bright for a star in an ultra-faint Milky Way (MW) satellite, we are able to measure the abundance of 28 elements, including 13 neutron-capture species. This star, DES J235532.66-593114.9 (DES J235532), shows a mild enhancement in neutron-capture elements associated with the r-process and can be classified as an r-I star. DES J235532 is the first r-I star to be discovered in an ultra-faint satellite, and Tuc III is the second extremely low-luminosity system found to contain r-process enriched material, after Reticulum II. Comparison of the abundance pattern of DES J235532 with r-I and r-II stars found in other dwarf galaxies and in the MW halo suggests a common astrophysical origin for the neutron-capture elements seen in all r-process enhanced stars. We explore both internal and external scenarios for the r-process enrichment of Tuc III and show that with abundance patterns for additional stars, it should be possible to distinguish between them.

Original languageEnglish (US)
Article number44
JournalAstrophysical Journal
Volume838
Issue number1
DOIs
StatePublished - Mar 20 2017

Keywords

  • galaxies: abundances
  • galaxies: dwarf
  • stars: abundances
  • stars: chemically peculiar

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Hansen, T. T., Simon, J. D., Marshall, J. L., Li, T. S., Carollo, D., Depoy, D. L., Nagasawa, D. Q., Bernstein, R. A., Drlica-Wagner, A., Abdalla, F. B., Allam, S., Annis, J., Bechtol, K., Benoit-Lévy, A., Brooks, D., Buckley-Geer, E., Rosell, A. C., Kind, M. C., Carretero, J., ... Walker, A. R. (2017). An r-process Enhanced Star in the Dwarf Galaxy Tucana III. Astrophysical Journal, 838(1), [44]. https://doi.org/10.3847/1538-4357/aa634a