Convective Effects on Mode Frequencies

Abstract

It is well known that the principal cause of the differences between measured and theoretical solar oscillation frequencies lies close to the solar surface, particularly in the narrow strongly-superadiabatic region. I shall discuss the details of these frequency residuals, and attempts to explain their existence by invoking structural changes in solar models and/or novel physics in the Sun or the oscillations. In general it will be found that, given the best atomic physics, hydrodynamics, and mode-physics available, the discrepancy between theory and observation can be considerably reduced compared to that found in simpler calculations. However there still remains a significant discrepancy which apparently indicates that the required perturbation to the solar structure is shallower than that implied by hydrodynamical simulation. In addition, no complete theory exists for the behaviour of significantly non-radial modes, of which the {\it f}\/-modes provide the paramount example.