Determination of non-LTE barium abundances in solar-type stars: A technique for non-LTE calculations

Abstract

Detailed statistical-equilibrium calculations are performed for the Ba II ion to elucidate the influence of non-LTE effects on barium abundances in the atmospheres of stars with Teff = 5500-6500 K, log g = 4.0 and 4.5, and [Fe/H] from -2 to 0. The computed non-LTE abundance corrections depend on the initial barium abundance εBa. They reverse sign as [Ba/H] changes from 0 to -2. The corrections are at a minimum for the λ5853 line (from -0.07 to +0.016 dex) and at a maximum for the λ6141 and 6496 lines (from -0.20 to +0.14 dex). In addition, the uncertainties in εBa resulting from errors in Teff, log g, and microturbulence ξt, as well as from the use of different model atmospheres and inaccuracies in the line-broadening parameters, are estimated.