HIGH-RESOLUTION SPECTROSCOPY OF EXTREMELY METAL-POOR STARS IN THE LEAST EVOLVED GALAXIES: LEO IV

Journal Article · Thu Jun 10 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/716/1/446· OSTI ID:21450846

Simon, Joshua D; McWilliam, Andrew; Thompson, Ian B ^[1]; Frebel, Anna ^[2]

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1. Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
2. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

We present high-resolution Magellan/MIKE spectroscopy of the brightest star in the ultra-faint dwarf galaxy Leo IV. We measure an iron abundance of [Fe/H] = -3.2, adding to the rapidly growing sample of extremely metal-poor (EMP) stars being identified in Milky Way satellite galaxies. The star is enhanced in the {alpha} elements Mg, Ca, and Ti by {approx}0.3 dex, very similar to the typical Milky Way halo abundance pattern. All of the light and iron-peak elements follow the trends established by EMP halo stars, but the neutron-capture elements Ba and Sr are significantly underabundant. These results are quite similar to those found for stars in the ultra-faint dwarfs Ursa Major II, Coma Berenices, Booetes I, and Hercules, suggesting that the chemical evolution of the lowest-luminosity galaxies may be universal. The abundance pattern we observe is consistent with predictions for nucleosynthesis from a Population III supernova explosion. The extremely low metallicity of this star also supports the idea that a significant fraction ({approx}>10%) of the stars in the faintest dwarfs have metallicities below [Fe/H] = -3.0.

• OSTI ID: 21450846
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 716; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
BARYON REACTIONS
ELECTROMAGNETIC PULSES
ELECTROMAGNETIC RADIATION
ELEMENTS
EVOLUTION
EXPLOSIONS
GALACTIC EVOLUTION
GALAXIES
HADRON REACTIONS
IRON
LUMINOSITY
METALS
MILKY WAY
NEUTRON REACTIONS
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUCLEOSYNTHESIS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PULSES
RADIATIONS
RESOLUTION
SPECTROSCOPY
STARS
SYNTHESIS
TRANSITION ELEMENTS