Astrophys. J., 738, 51 (2011/September-1)
The [Fe/H], [C/Fe], and [α/Fe] distributions of the Bootes I dwarf spheroidal galaxy.
LAI D.K., LEE Y.S., BOLTE M., LUCATELLO S., BEERS T.C., JOHNSON J.A., SIVARANI T. and ROCKOSI C.M.
Abstract (from CDS):
We present the results of a low-resolution spectral abundance study of 25 stars in the Boötes I dwarf spheroidal (dSph) galaxy. The data were obtained with the low resolution imaging spectrometer instrument at Keck Observatory and allow us to measure [Fe/H], [C/Fe], and [α/Fe] for each star. We find both a large spread in metallicity (2.1 dex in [Fe/H]) as well as a low average metallicity in this system, <[Fe/H]> = -2.59, matching previous estimates. This sample includes a newly discovered extremely metal-poor star, with [Fe/H] = -3.8, that is one of the most metal-poor stars yet found in a dSph. We compare the metallicity distribution function of Boötes I to analytic chemical evolution models. While the metallicity distribution function of Boötes I is best fit by an Extra Gas chemical evolution model, leaky-box models also provide reasonable fits. We also find that the [α/Fe] distribution and the carbon-enhanced metal-poor fraction of our sample (12%) are reasonable matches to Galactic halo star samples in the same metallicity range, indicating that at these low metallicities, systems like the Boötes I ultra-faint dSph could have been contributors to the Galactic halo.
galaxies: abundances - galaxies: dwarf - galaxies: individual: Bootes I - stars: abundances
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