Frequencies of solar global acoustic modes

The standard solar chemical composition of the late 2000s have the ratio of metals to hydrogen Z/X=0.0181, with a small increase to 0.0187 in 2021, as inferred from 3D non-LTE spectroscopy. However, more recent work on a horizontally and temporally averaged <3D> model claim Z/X=0.0225, consistent with the high values of twenty-five years ago based on 1D LTE spectroscopy.

We aim to determine a precise and robust value of the solar metal mass fraction from helioseismic inversions, thus providing independent constraints from spectroscopic methods. We devise a detailed seismic reconstruction technique of the solar envelope, combining multiple inversions and equations of state to accurately and precisely determine the metal mass fraction value. Results.