The Chemical Composition of the Solar Surface

TL;DR

This paper reviews the methods and challenges in determining the Sun's chemical composition, highlighting variations across different solar regions and the uncertainties involved in spectroscopic analysis.

Contribution

It provides a comprehensive overview of spectroscopic techniques and discusses the complexities in accurately measuring the Sun's chemical abundances.

Findings

Solar composition varies across different regions.

Uncertainties in abundance measurements often exceed 25%.

Spectroscopic analysis has inherent methodological pitfalls.

Abstract

The Sun provides a standard reference against which we compare the chemical abundances found anywhere else in the Universe. Nevertheless, there is not a unique 'solar' composition, since the chemical abundances found in the solar interior, the photosphere, the upper atmosphere, or the solar wind, are not exactly the same. The composition of the solar photosphere, usually preferred as a reference, changes with time due to diffusion, convection, and probably accretion. In addition, we do not know the solar photospheric abundances, inferred from the analysis of the solar spectrum using model atmospheres, with high accuracy, and uncertainties for many elements exceed 25%. This paper gives an overview of the methods and pitfalls of spectroscopic analysis, and discusses the chemistry of the Sun in the context of the solar system.