New Stellar Parameters, Metallicities, and Elemental Abundance Ratios for 311 Metal-poor Stars

Abstract

We present equivalent widths, improved model atmosphere parameters, and revised abundances for 14 species of 11 elements derived from high-resolution optical spectroscopy of 311 metal-poor stars. All of these stars had their parameters previously published by Roederer et al. We use color–T_eff relationships calibrated for Gaia and 2MASS photometry to calculate improved effective temperatures (T_eff). We calculate log of surface gravity (log g) values using measurements derived from Gaia parallaxes and other fundamental stellar properties. We perform a standard LTE abundance analysis using MARCS model atmospheres and the MOOG line analysis software to rederive microturbulence velocity parameters, metallicities, and abundances based on O I, Na I, Mg I, Si I, K I, Ca I, Ti I, Ti II, Cr I, Cr II, Fe I, Fe II, Ni I, and Zn I lines using previously measured equivalent widths. On average, the new T_eff values are 310 K warmer, the new log g values are higher by 0.64 dex, and the new [Fe/H] values are higher by 0.26 dex. We apply NLTE corrections to the abundances derived from O I, Na I, Mg I, Si I, K I, Fe I, and Fe II lines. Our sample contains 6 stars with [Fe/H] < ‑3.5, 28 stars with [Fe/H] < ‑3.0, and 113 stars with [Fe/H] < ‑2.5. Our revised abundances for these 311 stars are now in better agreement with those derived by previous studies of smaller samples of metal-poor stars in the Milky Way.