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Detailed abundance analysis of the brightest star in Segue 2, the least massive galaxy

Roederer, Ian U. and Kirby, Evan N. (2014) Detailed abundance analysis of the brightest star in Segue 2, the least massive galaxy. Monthly Notices of the Royal Astronomical Society, 440 (3). pp. 2665-2675. ISSN 0035-8711. doi:10.1093/mnras/stu491.

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We present the first high-resolution spectroscopic observations of one red giant star in the ultra-faint dwarf galaxy Segue 2, which has the lowest total mass (including dark matter) estimated for any known galaxy. These observations were made using the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the Magellan II Telescope at Las Campanas Observatory. We perform a standard abundance analysis of this star, SDSS J021933.13+200830.2, and present abundances of 21 species of 18 elements as well as upper limits for 25 additional species. We derive [Fe/H] = −2.9, in excellent agreement with previous estimates from medium-resolution spectroscopy. Our main result is that this star bears the chemical signatures commonly found in field stars of similar metallicity. The heavy elements produced by neutron-capture reactions are present, but they are deficient at levels characteristic of stars in other ultra-faint dwarf galaxies and a few luminous dwarf galaxies. The otherwise normal abundance patterns suggest that the gas from which this star formed was enriched by metals from multiple Type II supernovae reflecting a relatively well-sampled IMF. This adds to the growing body of evidence indicating that Segue 2 may have been substantially more massive in the past.

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URLURL TypeDescription Paper
Kirby, Evan N.0000-0001-6196-5162
Additional Information:© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 March 7. Received 2014 March 7; in original form 2014 January 22. Published: 09 April 2014. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. IUR thanks J. Sobeck and C. Sneden for their expert assistance with MOOG. We thank the referee for providing helpful suggestions on the manuscript. This research has made use of NASA's Astrophysics Data System Bibliographic Services, the arXiv preprint server operated by Cornell University, the SIMBAD and VizieR data bases hosted by the Strasbourg Astronomical Data Center, and the Atomic Spectra Database (Kramida et al. 2013) hosted by the National Institute of Standards and Technology. IRAF is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation. ENK acknowledges support from the Southern California Center for Galaxy Evolution, a multicampus research program funded by the University of California Office of Research, and partial support from NSF grant AST-1009973.
Funding AgencyGrant Number
Southern California Center for Galaxy EvolutionUNSPECIFIED
University of CaliforniaUNSPECIFIED
Subject Keywords:nuclear reactions, nucleosynthesis, abundances – stars: abundances – stars: individual: SDSS J021933.13+200830.2 – galaxies: individual: Segue 2
Issue or Number:3
Record Number:CaltechAUTHORS:20190514-120114668
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Official Citation:Ian U. Roederer, Evan N. Kirby, Detailed abundance analysis of the brightest star in Segue 2, the least massive galaxy, Monthly Notices of the Royal Astronomical Society, Volume 440, Issue 3, 21 May 2014, Pages 2665–2675,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95491
Deposited By: Tony Diaz
Deposited On:14 May 2019 20:31
Last Modified:16 Nov 2021 17:13

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