THE [Fe/H], [C/Fe], AND [α/Fe] DISTRIBUTIONS OF THE BOOTES I DWARF SPHEROIDAL GALAXY

被引：89

作者：

Lai, David K. ^{[1
]}

Lee, Young Sun ^{[2
,3
]}

Bolte, Michael ^{[1
]}

Lucatello, Sara ^{[4
]}

Beers, Timothy C. ^{[2
,3
]}

Johnson, Jennifer A. ^{[5
]}

Sivarani, Thirupathi ^{[6
]}

Rockosi, Constance M. ^{[1
]}

机构：

[1] Univ Calif Santa Cruz, Univ Calif Observ, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA

[2] Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA

[3] Michigan State Univ, JINA Joint Inst Nucl Astrophys, E Lansing, MI 48824 USA

[4] Osserv Astron Padova, I-35122 Padua, Italy

[5] Ohio State Univ, Dept Astron, Columbus, OH 43210 USA

[6] Indian Inst Astrophys, Bangalore 560034, Karnataka, India

来源：

ASTROPHYSICAL JOURNAL | 2011年 / 738卷 / 01期

基金：

美国国家科学基金会;

关键词：

galaxies: abundances; galaxies: dwarf; galaxies: individual (Bootes I); stars: abundances; METAL-POOR STARS; MULTIELEMENT ABUNDANCE MEASUREMENTS; HIGH-RESOLUTION SPECTROSCOPY; MILKY-WAY SATELLITE; DIGITAL SKY SURVEY; SEGUE; SYSTEM; CHEMICAL ABUNDANCES; GLOBULAR-CLUSTERS; FUNDAMENTAL LINE; FORMING GALAXIES;

D O I：

10.1088/0004-637X/738/1/51

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present the results of a low-resolution spectral abundance study of 25 stars in the Bootes 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 [alpha/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 Bootes I to analytic chemical evolution models. While the metallicity distribution function of Bootes I is best fit by an Extra Gas chemical evolution model, leaky-box models also provide reasonable fits. We also find that the [alpha/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 Bootes I ultra-faint dSph could have been contributors to the Galactic halo.

引用

页数：10

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