Non-LTE oxygen line formation in 3D hydrodynamic model stellar atmospheres

TL;DR

This paper investigates non-LTE effects on oxygen line formation in 3D stellar atmospheres, providing grids of corrections for more accurate oxygen abundance measurements in FGK stars.

Contribution

It introduces a comprehensive analysis of non-LTE effects on oxygen lines using 3D hydrodynamic models, offering new correction grids for stellar abundance studies.

Findings

Significant non-LTE departures for OI 777 nm lines.

Departures increase with higher temperature, lower gravity, and higher oxygen abundance.

Provides correction grids for multiple oxygen lines.

Abstract

The OI 777 nm lines are among the most commonly used diagnostics for the oxygen abundances in the atmospheres of FGK-type stars. However, they form in conditions that are far from local thermodynamic equilibrium (LTE). We explore the departures from LTE of atomic oxygen, and their impact on OI lines, across the Stagger-grid of three-dimensional hydrodynamic model atmospheres. For the OI 777 nm triplet we find significant departures from LTE. These departures are larger in stars with larger effective temperatures, smaller surface gravities, and larger oxygen abundances. We present grids of predicted 3D non-LTE based equivalent widths for the OI616nm, [OI] 630 nm, [OI] 636 nm, and OI 777 nm lines, as well as abundance corrections to 1D LTE based results.