Source of excitation of low- solar p modes: characteristics and solar-cycle variations

Abstract

We investigate various properties of the excitation source that is responsible for driving the acoustic p-mode oscillations of the Sun. Current prejudice places this in the superadiabatic layer of the convection zone. We consider in detail how the precise nature of the resonant mode spectrum is modified: (i) as a result of the impact of different source-multipole mixtures; and (ii) as a function of the radial extent of the source. To do this, we model the observed resonant spectra with the solutions to a simple, one-dimensional wave equation which is intended to describe the essential elements of the solar resonant acoustic cavity, Further, we also fit these models to the low-l peaks in a high-resolution power spectrum generated from data collected by the Birmingham Solar-Oscillations Network (BiSON), We also use the extensive BiSON data set to search for variations in the source characteristics over the solar cycle.