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

The O i 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 O i lin...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2016-02, Vol.455 (4), p.3735-3751
Main Authors: Amarsi, A. M., Asplund, M., Collet, R., Leenaarts, J.
Format: Article
Language:English
Subjects:
Astronomy
Computational fluid dynamics
Equivalence
Fluid flow
Fluid mechanics
Hydrodynamics
line: formation
Mathematical models
methods: numerical
Oxygen
radiative transfer
Stars
Stars & galaxies
stars: abundances
stars: atmospheres
Stellar atmospheres
Thermodynamics
Three dimensional models
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Summary:The O i 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 O i lines, across the stagger-grid of three-dimensional hydrodynamic model atmospheres. For the O i 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 O i 616 nm, [O i] 630 nm, [O i] 636 nm, and O i 777 nm lines, as well as abundance corrections to 1D LTE based results.
ISSN:0035-8711
1365-2966
1365-2966
DOI:10.1093/mnras/stv2608