Chemical Abundances Of The Leo II Dwarf Galaxy

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dc.contributor.utaustinauthorShetrone, Matthew D.en_US
dc.contributor.utaustinauthorSiegel, Michael H.en_US
dc.creatorShetrone, Matthew D.en_US
dc.creatorSiegel, Michael H.en_US
dc.creatorCook, David O.en_US
dc.creatorBosler, Tammyen_US
dc.date.accessioned2016-04-22T19:48:00Z
dc.date.available2016-04-22T19:48:00Z
dc.date.issued2009-01en
dc.description.abstractWe use previously published moderate-resolution spectra in combination with stellar atmosphere models to derive the first measured chemical abundance ratios in the Leo II dwarf Spheroidal (dSph) galaxy. We find that for spectra with signal-to-noise ratio greater than 24, we are able to measure abundances from weak Ti, Fe, and Mg lines located near the calcium infrared triplet (CaT). We also quantify and discuss discrepancies between the metallicities measured from Fe I lines and those estimated from the CaT features. We find that while the most metal-poor ([Fe/H] < - 2.0]) Leo II stars have Ca and Ti abundance ratios similar to those of Galactic globular clusters, the more metal-rich stars show a gradual decline of Ti, Mg, and Ca abundance ratio with increasing metallicity. Finding these trends in this distant and apparently dynamically stable dSph galaxy supports the hypothesis that the slow chemical enrichment histories of the dSph galaxies is universal, independent of any interaction with the Milky Way. Combining our spectroscopic abundances with published broadband photometry and updated isochrones, we are able to approximate stellar ages for our bright red giant branch stars to a relative precision of 2-3 Gyr. While the derived age-metallicity relationship of Leo II hints at some amount of slow enrichment, the data are still statistically consistent with no enrichment over the history of Leo II.en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipNSF AST-0649128, AST-0306884en_US
dc.identifierdoi:10.15781/T2G805
dc.identifier.citationShetrone, Matthew D., Michael H. Siegel, David O. Cook, and Tammy Bosler. >Chemical Abundances of the Leo II Dwarf Galaxy.> The Astronomical Journal 137, No. 1 (Jan., 2009): pp. 62.en_US
dc.identifier.doi10.1088/0004-6256/137/1/62en_US
dc.identifier.issn0004-6256en_US
dc.identifier.urihttp://hdl.handle.net/2152/34521
dc.language.isoEnglishen_US
dc.relation.ispartofserialAstronomical Journalen_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.subjectgalaxies: dwarfen_US
dc.subjectgalaxies: evolutionen_US
dc.subjectgalaxies: individual (leo ii)en_US
dc.subjectstars: abundancesen_US
dc.subjectexploring halo substructureen_US
dc.subjectgalactic globular-clustersen_US
dc.subjectbaades windowen_US
dc.subjectgiantsen_US
dc.subjectkeck hires spectraen_US
dc.subjectmetal-poor starsen_US
dc.subjectspheroidal galaxyen_US
dc.subjectstellaren_US
dc.subjectpopulationsen_US
dc.subjectomega-centaurien_US
dc.subjectacs surveyen_US
dc.subjectvlt/uves abundancesen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleChemical Abundances Of The Leo II Dwarf Galaxyen_US
dc.typeArticleen_US

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