Extremely Metal‐poor Stars. II. Elemental Abundances and the Early Chemical Enrichment of the Galaxy

We have obtained high-resolution spectra of 23 very metal-poor stars and present an abundance analysis for 19 of these for elements between Mg and Eu. The sample comprises roughly equal numbers of dwarfs and giants. All stars have Fe/H < −2.5, and 10 have Fe/H < −3.0. In addition, for six stars with Fe/H < −3.0, we compile equivalent widths from the literature (including our own studies) and recompute abundances. Possible errors in the stellar atmospheric models are discussed in detail. Hyperfine-structure corrections are presented for Mn and Co. We use robust techniques to delineate the main trends in the X/Fe versus Fe/H plots and compare these with the Galactic chemical evolution computations of Timmes, Woosley, & Weaver.