Chemical Compositions of Four Metal-poor Giant Stars

Abstract

We present the chemical compositions of four K giants (CS 22877-1, CS 22166-16, CS 22169-35, and BS 16085-0050) that have [Fe/H] in the range -2.4 to -3.1. Metal-poor stars with [Fe/H]<-2.5 are known to exhibit considerable star-to-star variations of many elements. This quartet confirms this conclusion. CS 22877-1 and CS 22166-16 are carbon-rich. There is significant spread of [α/Fe] within our samples, where [α/Fe] is computed from the mean of the [Mg/Fe] and [Ca/Fe] ratios. BS 16085-0050 is remarkably α-enriched with a mean [α/Fe] of +0.7, but CS 22169-35 is α-poor. The aluminum abundance also shows a significant variation over the sample. A parallel and unsuccessful search among high-velocity late-type stars for metal-poor stars is described.