Helioseismic measurement of element abundances in the solar interior

Inversions of the current solar data give a value for the helium abundance in the convection zone, which is significantly lower than the value in standard solar models, thus suggesting that gravitational settling of helium takes place in the Sun. This is consistent with the inversion results in the radiative interior, where evidence is found for large-scale material redistribution. There is also indication of variations of the helium abundance in the energy-generating core, which are not described by standard solar evolution theory.