Inelastic processes in strontium-hydrogen collisions and their impact on non-LTE calculations

TL;DR

This paper calculates inelastic collision rate coefficients for strontium-hydrogen interactions using a quantum model, updates the Sr II atom model, and assesses their impact on non-LTE abundance corrections in metal-poor stars.

Contribution

It provides new quantum data for Sr-H collisions and demonstrates their significance in non-LTE modeling of stellar atmospheres.

Findings

Calculated 1202 partial process rate coefficients.

Updated Sr II model atom with new quantum data.

Provided non-LTE abundance corrections for metal-poor stars.

Abstract

Inelastic processes rate coefficients for low-energy Sr + H, Sr$^+$ + H$^-$, Sr$^+$ + H and Sr$^{2+}$ + H$^-$ collisions are calculated using multichannel quantum model approach. 31 scattering channels of SrH$^+$ and 17 scattering channels of SrH are considered. The partial cross sections and the partial rate coefficients are hence calculated for 1202 partial processes in total. Using new quantum data for Sr II + H I collisions, we updated model atom of Sr II and performed the non-local thermodynamic equilibrium (non-LTE) calculations. We provide the non-LTE abundance corrections for the Sr II resonance lines in two grids of model atmospheres, which are applicable to very metal-poor ([Fe/H] $\le -2$) dwarfs and giants.