On the Abundance of Potassium in Metal-Poor Stars

Abstract

Abstract Based on extensive statistical-equilibrium calculations, we performed a non-LTE analysis of the K i 7699 equivalent-width data of metal-deficient stars for the purpose of clarifying the behavior of the photospheric potassium abundance in disk/halo stars. While the resulting non-LTE abundance corrections turned out to be considerably large, amounting to 0.2–0.7 dex, their effect on the [K/Fe] vs. [Fe/H] relation is not very important, since these corrections do not show any significant dependence on the metallicity. Hence, we again confirmed the results of previous LTE studies, that [K/Fe] shows a gradual systematic increase toward a lowered metallicity up to [K/Fe] $sim$ 0.3–0.5 at [Fe/H] $sim$-1 to -2, such as in the case of $ \alpha$ elements.