Influence of Inelastic Collisions with Hydrogen Atoms on Non-LTE Oxygen Abundance Determination in the Sun and late-type stars

TL;DR

This study uses updated quantum-mechanical data to perform non-LTE calculations for oxygen in the Sun and stars, revealing more accurate oxygen abundances and a revised [O/Fe] trend across different metallicities.

Contribution

It introduces improved non-LTE modeling with quantum-mechanical collision data, refining oxygen abundance measurements in stars compared to previous methods.

Findings

Non-LTE effects lead to larger oxygen abundance corrections.

Revised [O/Fe]-[Fe/H] trend shows increased [O/Fe] at low metallicities.

Infrared triplet lines' abundance change decreases with lower metallicity.

Abstract

We present the non-local thermodynamic equilibrium (non-LTE) calculations for O I with the updated model atom that includes quantum-mechanical rate coefficients for O I + H I inelastic collisions from the recent study of Barklem (2018). The non-LTE abundances from the O I lines were determined for the Sun and 46 FG stars in a wide metallicity range, -2.6 < [Fe/H] < 0.2. An application of accurate atomic data leads to larger departures from LTE and lower oxygen abundances compared to that for the Drawin's theoretical approximation. For the infrared O I 7771-5 A triplet lines, the change in the non-LTE abundance is -0.11 dex for the solar atmospheric parameters and decreases in absolute value towards lower metallicity. We revised the [O/Fe]-[Fe/H] trend derived in our earlier study. The change in [O/Fe] is small in the [Fe/H] range from -1.5 to 0.2. For stars with [Fe/H] < -1, the [O/Fe] ratio has increased such that [O/Fe] = 0.60 at [Fe/H] = -0.8 and increases up to [O/Fe] = 0.75 at [Fe/H] = -2.6.