THE [Fe/H], [C/Fe], AND [{alpha}/Fe] DISTRIBUTIONS OF THE BOOeTES I DWARF SPHEROIDAL GALAXY

Journal Article · Thu Sep 01 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/738/1/51· OSTI ID:21582935

Lai, David K; Bolte, Michael; Rockosi, Constance M ^[1]; Lee, Young Sun; Beers, Timothy C ^[2]; Lucatello, Sara ^[3]; Johnson, Jennifer A ^[4]; Sivarani, Thirupathi ^[5]

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1. University of California Observatories/Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
2. Department of Physics and Astronomy and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States)
3. Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padua (Italy)
4. Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210 (United States)
5. Indian Institute of Astrophysics, 2nd Block Koramangala, Bangalore 560034 (India)

We present the results of a low-resolution spectral abundance study of 25 stars in the Booetes 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 Booetes I to analytic chemical evolution models. While the metallicity distribution function of Booetes 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 Booetes I ultra-faint dSph could have been contributors to the Galactic halo.

• OSTI ID: 21582935
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 738; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
CARBON
DISTRIBUTION FUNCTIONS
ELEMENT ABUNDANCE
ELEMENTS
FUNCTIONS
GALAXIES
HYDROGEN
IRON
IRON-ALPHA
METALS
NONMETALS
STARS
TRANSITION ELEMENTS