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

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    50 Citations (Scopus)

    Abstract

    © 2017. The American Astronomical Society. All rights reserved.. 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
    Article number44
    JournalAstrophysical Journal
    Volume838
    Issue number1
    DOIs
    Publication statusPublished - 20 Mar 2017

    Keywords

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

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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