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

作者：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 Levy A; Brooks D; Buckley Geer E; Carnero Rosell A; Kind M Carrasco; Carretero J; Cunha C E; da Costa L N; Desai S; Eifler T F; Fausti Neto A; Flaugher B; Frieman J; Garcia Bellido J; Gaztanaga E; Gerdes D W; Gruen D; Gruendl R A; Gschwend J; Gutierrez G

来源：Astrophysical Journal, 2017, 838(1): 44.

DOI：10.3847/1538-4357/aa634a

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

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.

• 出版日期2017-3-20