Uncovering Extremely Metal-Poor Stars in the Milky Way's Ultrafaint Dwarf Spheroidal Satellite Galaxies

dc.contributor.utaustinauthorFrebel, Annaen_US
dc.creatorKirby, Evan N.en_US
dc.creatorSimon, Joshua D.en_US
dc.creatorGeha, Marlaen_US
dc.creatorGuhathakurta, Puragraen_US
dc.creatorFrebel, Annaen_US
dc.date.accessioned2016-10-28T19:36:47Z
dc.date.available2016-10-28T19:36:47Z
dc.date.issued2008-09en_US
dc.description.abstractWe present new metallicity measurements for 298 individual red giant branch stars in eight of the least luminous dwarf spheroidal galaxies (dSphs) in the Milky Way ( MW) system. Our technique is based on medium-resolution Keck DEIMOS spectroscopy coupled with spectral synthesis. We present the first spectroscopic metallicities at of stars in a dwarf galaxy, with individual stellar metallicities as low as. Because [Fe/H] < -3.0 [Fe/H] = -3.3 our [Fe/H] measurements are not tied to empirical metallicity calibrators and are sensitive to arbitrarily low metallicities, we are able to probe this extremely metal-poor regime accurately. The metallicity distribution of stars in these dSphs is similar to the MW halo at the metal-poor end. We also demonstrate that the luminosity-metallicity relation previously seen in more luminous dSph galaxies (M(v) = -13.4 to -8.8) extends smoothly down to an absolute magnitude of M(v) = -3.7. The discovery of extremely metal-poor stars in dSphs lends support to the Lambda CDM galaxy assembly paradigm wherein dwarf galaxies dissolve to form the stellar halo of the MW.en_US
dc.description.departmentMcDonald Observatoryen_US
dc.description.sponsorshipNational Science Foundation AST 03-07966, AST 06-07852en_US
dc.description.sponsorshipNASA/STScI GO-10265.02, GO-10134.02en_US
dc.description.sponsorshipNSFen_US
dc.description.sponsorshipMcDonald Observatoryen_US
dc.identifierdoi:10.15781/T2C824H49
dc.identifier.citationKirby, Evan N., Joshua D. Simon, Marla Geha, Puragra Guhathakurta, and Anna Frebel. "Uncovering Extremely Metal-Poor Stars in the Milky Way’s Ultrafaint Dwarf Spheroidal Satellite GalaxiesData herein were obtained at the WM Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the WM Keck Foundation." The Astrophysical Journal Letters, Vol. 685, No. 1 (Sep., 2008): L43.en_US
dc.identifier.doi10.1086/592432en_US
dc.identifier.issnen_US
dc.identifier.urihttp://hdl.handle.net/2152/43034
dc.language.isoEnglishen_US
dc.relation.ispartofen_US
dc.relation.ispartofserialAstrophysical Journal Lettersen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.rights.restrictionOpenen_US
dc.subjectgalaxies: abundancesen_US
dc.subjectgalaxies: dwarfen_US
dc.subjectgiant southern streamen_US
dc.subjectgalactic haloen_US
dc.subjectstructural-propertiesen_US
dc.subjectvlt/uvesen_US
dc.subjectabundancesen_US
dc.subjectchemical abundancesen_US
dc.subjectstellar kinematicsen_US
dc.subjectway satellitesen_US
dc.subjectbranch starsen_US
dc.subjectcaii tripleten_US
dc.subjectsmall scalesen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleUncovering Extremely Metal-Poor Stars in the Milky Way's Ultrafaint Dwarf Spheroidal Satellite Galaxiesen_US
dc.typeArticleen_US
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