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First Stars III
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Poster
Title: Beryllium in the Oldest Stars Author(s): Ann M. Boesgaard Abstract: Beryllium, oxygen and iron abundances have been determined in halo dwarf stars with [Fe/H] between -0.9 and -3.5. The spectra were obtained at high resolution (~48,000) and high signal-to-noise (80-150) with the upgraded HIRES on the Keck-I 10-m telescope. These spectra have been used to determine the stellar parameters: temperature, log g and [Fe/H]. The Be abundances have been found by spectrum synthesis of the Be II doublet at 3130.4 and 3131.1 A. Our sample also includes 4 stars observed with HDS on the Subaru 8-m telescope (Boesgaard & Novicki 2006) and 14 stars reanalyzed from Boesgaard et al. (1999) with the latest version of MOOG. Newly determined O abundances are found from three OH lines in the UV. We show the relationships between Be and [Fe/H], [O/H], and [O/Fe] and [Be/Fe] vs. [Fe/H] for the whole sample to trace the Galactic evolution of these elements. In addition we subdivide sample into accretive and dissipative populations to examine possible differences.
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