Low-degree solar rotational splitting from 45 yr of BiSON observations

The splitting values are estimated from the power spectrum using a Markov chain Monte Carlo sampling method, and we also present for comparison the results from an analysis of 100 realizations of synthetic data with the same resolution and gap structure.

Comparison of the scatter in the results from the synthetic realizations with their estimated uncertainties suggests that for this data set the formal uncertainty estimates are about 30 per cent too small. An upward bias in the splittings at frequencies above 2200 μHz, where the components are not fully resolved, is seen in both the observed and synthetic data. When this bias is taken into account, our results are consistent with a frequency-independent synodic rotational splitting value of 400 nHz.