Skew-symmetric solar p modes in low-l BiSON data

The p-mode oscillations of the Sun are manifestations of resonantly trapped acoustic waves propagating within its interior. The effective size of the resulting resonant cavity changes with the properties of the modes - the interaction of this phenomenon with a highly localized excitation source in the upper layers of the convection zone gives rise to skew-symmetric resonant profiles whose degree of asymmetry changes with frequency. Here, we have fitted low-angular-degree (low-l) resonant p-mode peaks - in a power spectrum generated from 32 months of BiSON Doppler velocity observations of the visible solar disc - to a skew-symmetric formalism to account for this effect. We present the fitted frequencies, fine-structure spacings [d(0)(n) and d(1)(n)] and mode-skewness estimates; and discuss the quantitative impact of fitting a skew, rather than symmetric, limit model. We also consider the reliability of the extracted parameters through the application of a useful statistical test, and extensive Monte Carlo fits to artificial data.