2012A&A...546A..90B

We investigate the statistical equilibrium of neutral and singly-ionized strontium in late-type stellar atmospheres. Particular attention is given to the completeness of the model atom, which includes new energy levels, transition probabilities, photoionization and electron-impact excitation cross-sections computed with the R-matrix method. The NLTE model is applied to the analysis of SrI and SrII lines in the spectra of the Sun, Procyon, Arcturus, and HD 122563, showing a significant improvement in the ionization balance compared to LTE line formation calculations, which predict abundance discrepancies of up to 0.5dex. The solar Sr abundance is logε=2.93±0.04dex, in agreement with the meteorites. We present the grid of NLTE abundance corrections for SrI and SrII lines that covers a wide range of stellar parameters.