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arXiv · 2509.05225

The solar sulphur abundance in view of large-scale atomic structure calculations and 3D non-LTE models

A. M. Amarsi·W. Li·N. Grevesse·A. J. G. Jurewicz
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Abstract

The solar chemical composition is a fundamental yardstick in astrophysics and the topic of heated debate in recent literature. We re-evaluate the abundance of sulphur in the photosphere by studying seven S I lines in the solar disc-centre intensity spectrum. Our analysis considers independent sets of experimental and theoretical oscillator strengths together with, for the first time, three-dimensional non-local thermodynamic equilibrium (3D non-LTE) S I spectrum synthesis. Our best estimate is $A(\mathrm{S})=7.06\pm0.04$, which is $0.06$ dex to $0.10$ dex lower than that in commonly-used compilations of the solar chemical composition. Our lower solar sulphur abundance deviates from that in CI chondrites, and thereby supports the case for a systematic difference between the composition of the solar photosphere and of CI chondrites that is correlated with $50\%$ condensation temperature. We suggest that precise laboratory measurements of S I oscillator strengths and abundance analyses using 3D magnetohydrodynamic models of the solar photosphere be conducted to further substantiate our conclusions.

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A. M. Amarsi, W. Li, N. Grevesse, A. J. G. Jurewicz. 2025-09-05. The solar sulphur abundance in view of large-scale atomic structure calculations and 3D non-LTE models. https://doi.org/10.1051/0004-6361%2F202556728

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