Monday

Sunspots have been observed to torsionally rotate about their umbral centres, and in some cases may rotate 100-300 degrees over the course of 10 days. There are many case studies in the literature that link sunspot rotation to solar activity, such as solar flares, CMEs, and sigmoids, but as yet there is little statistical evidence for this.

In this talk we present two statistical samples of rotating sunspots which are associated with solar flares. One is a high-energy flare sample where sunspots are linked to X-class flares, and the other is a low-energy flare sample based on a 4 month time period.

Energy input from sunspot rotation is estimated in each case using a helicity calculation and an empirical energy scaling, and compared to the output radiated flare energy to demonstrate that in the majority of cases the sunspot rotation provides sufficient energy to account for the radiated flare energy.

These samples show that not only is there a relation between sunspot rotation and solar flares, but that sunspot rotation also injects sufficient energy into the solar atmosphere to power the flares.