Abstract

Abstract We revisit the Galactic chemical evolution of oxygen, addressing the systematic errors inherent in classical determinations of the oxygen abundance that arise from the use of one-dimensional (1D) hydrostatic model atmospheres and from the assumption of local thermodynamic equilibrium (LTE). We perform detailed 3D non-LTE radiative-transfer calculations for atomic oxygen lines across a grid of 3D hydrodynamic stagger model atmospheres for dwarfs and subgiants. We apply our grid of predicted line strengths of the [O i] 630 nm and O i 777 nm lines using accurate stellar parameters from the literature. We infer a steep decay in [O/Fe] for [Fe/H] ≳ −1.0, a plateau [O/Fe] ≈ 0.5 down to [Fe/H] ≈ −2.5, and an increasing trend for [Fe/H] ≲ −2.5. Our 3D non-LTE calculations yield overall concordant results from the two oxygen abundance diagnostics.

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