Solar p-mode excitation: further insight from recent low-l BiSON helioseismological data

We present measurements of low-degree solar p-mode velocity powers, energies and energy supply rates between similar to 1600 mu Hz and similar to 4700 mu Hz, as derived from the analysis of several years of high-quality helioseismological data collected by the Birmingham Solar-Oscillations Network (BiSON). For the radial (l = 0) modes, we find that the total energy E per mode (kinetic plus potential) peaks at similar to 3200 mu Hz, reaching approximate to 10(28) erg. The rate at which energy is supplied to the modes (E) over dot = 2 pi Delta nu . E, where Delta nu is the FWHM modal line width, is observed to plateau between similar to 3000 and similar to 4000 mu Hz, reaching a maximum of approximate to 10(23) erg s(-1). At frequencies below the plateau, the supply rate follows a simple power law with a dependence of (E) over dot proportional to nu(7.0+/-0.4); and at very-high frequencies the data follow (E) over dot proportional to nu(-4.5+/-1.1). These assume modal inertias normalized at T = T-eff; with the mode-mass calculation normalized at the optical depth of the BiSON observations, the fitted power laws in (E) over dot are approximately similar to nu(6.5+/-1.1) and similar to nu(-6.2+/-1.1) respectively.