BiSON observations, their application to the rotation of the solar interior and to excitation mechanisms - the advantages of long, continuous time series

Abstract

The Birmingham Solar Oscillations group runs the so-called BiSON network. As the network has been operational since 1981 we have the great advantage of long, well-filled, historical datasets. These data have been put to many uses of which two are highlighted here. We have recently been able to use 16-month spectra with good fill to measure, unambiguously, the rotational splitting of low-l p-modes at frequencies where, although the modes are very weak, they have line widths which are significantly less than the line splitting. This has lead to the conclusion that the core of the Sun probably rotates slowly, possibly at the same rate as the rest of the radiative interior. The other issue which is addressed is the use of short transforms to follow the evolution of individual modes. The analysis gives strong support to the stochastic excitation mechanism and allows one to measure decay times and other mode parameters directly.