A study of torsional sunspot motion

A fundamental understanding of the behaviour of sunspots is a powerful tool by which plasma dynamics and magnetism of the solar interior can also be better understood. Here a straightforward method is presented to investigate the temporal evolution of various sunspot features. Our particular aim is to detect rotations and search for oscillations in the torsional motions. We demonstrate the method by using the SOHO/MDI (Michelson Doppler Imager on board the Solar and Heliospheric Observatory) white-light intensity continuum images of a sunspot, which was visible on the solar disc between 17th and 28th July 2003.