Chemical Composition of Faint (I ~ 21 mag) Microlensed Bulge Dwarf OGLE-2007-BLG-514S

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Title: Chemical Composition of Faint (I ~ 21 mag) Microlensed Bulge Dwarf OGLE-2007-BLG-514S
Creators: Epstein, Courtney R.; Johnson, Jennifer A.; Dong, Subo; Udalski, Andrzej; Gould, Andrew; Becker, George
Keywords: Galaxy: bulge
Galaxy: evolution
gravitational lensing: micro
stars: abundances
Issue Date: 2010-01-10
Publisher: American Astronomical Society
Citation: Courtney R. Epstein et al, "Chemical Composition of Faint (I ~ 21 mag) Microlensed Bulge Dwarf OGLE-2007-BLG-514S," The Astrophysical Journal 709, no. 1 (2010), doi:10.1088/0004-637X/709/1/447
DOI: 10.1088/0004-637X/709/1/447
Abstract: We present a high-resolution spectrum of a microlensed G dwarf in the Galactic bulge with spectroscopic temperature T_eff = 5600 ± 180 K. This I ~ 21 mag star was magnified by a factor ranging from 1160 to 1300 at the time of observation. Its high metallicity ([Fe/H] = 0.33 ± 0.15 dex) places this star at the upper end of the bulge giant metallicity distribution. Using a Kolmogorov-Smirnov test, we find a 1.6% probability that the published microlensed bulge dwarfs share an underlying distribution with bulge giants, properly accounting for a radial bulge metallicity gradient. We obtain abundance measurements for 15 elements and perform a rigorous error analysis that includes covariances between parameters. This star, like bulge giants with the same metallicity, shows no alpha enhancement. It confirms the chemical abundance trends observed in previously analyzed bulge dwarfs. At supersolar metallicities, we observe a discrepancy between bulge giant and bulge dwarf Na abundances.
ISSN: 1538-4357
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