Solar oxygen abundance using SST/CRISP center-to-limb observations of the O I 7772 \r{A} line

TL;DR

This study uses SST/CRISP observations of the O I 7772 Å line across the solar disk to validate 3D NLTE models, resulting in a precise solar oxygen abundance measurement with minimal angular variation.

Contribution

It provides the first comprehensive test of 3D NLTE line formation models across the solar disk using high-resolution spectroscopic mosaics.

Findings

3D NLTE models accurately describe line formation across the solar disk.

Derived solar oxygen abundance is A(O) = 8.73 ± 0.03 dex.

Spectroscopic mosaics are effective for testing hydrodynamics and line formation models.

Abstract

Solar oxygen abundance measurements based on the O I near-infrared triplet have been a much-debated subject for several decades since non-local thermodynamic equilibrium (NLTE) calculations with 3D radiation-hydrodynamics model atmospheres introduced a large change to the 1D LTE modelling. In this work, we aim to test solar line formation across the solar disk using new observations obtained with the SST/CRISP instrument. The observed dataset is based on a spectroscopic mosaic stretching from disk center to the solar limb. By comparing the state-of-the-art 3D NLTE models with the data, we find that the 3D NLTE models provide an excellent description of line formation across the disk. We obtain an abundance value of $A(\mathrm{O}) = (8.73 \pm 0.03)$ dex, with a very small angular dispersion across the disk. We conclude that spectroscopic mosaics are excellent probes for geometric and physical properties of hydrodynamics models and non-LTE line formation.