Abstract Sunspots have been observed to undergo rotation about their umbral centre. This is typically a slow rotation, with even the fastest sunspot rotations only reaching angular velocities of few degrees per hour. may inject magnetic energy into Sun’s atmosphere, which can be stored in coronal field and later released eruptive events such as solar flares mass ejections. To usefully investiga...

Rotation is a general phenomenon in astrophysical systems on scales from planets to giant galaxy clusters. It is established during the formation of the system under gravitational compression. Typically the rotation rate is greatly enhanced during this process (Thompson et al. 2003). Rotation of stars defines their shapes and drives the internal circulation which redistributes chemical elements...

In recent years, speckle interferometry has been successfully applied to various solar phenomena and provides a powerful tool to study solar small-scale structures. The present investigation lays special emphasis on sunspots and sunspot pores. The observations have been performed with the Vacuum Tower Telescope (VTT) at the Observatorio del Teide (Tenerife) in the years from 1992 to 1994. Time ...

In a recent paper (Švanda et al., 2008, A&A 477, 285) we pointed out that, based on the tracking of Doppler features in the full-disc MDI Dopplergrams, the active regions display two dynamically different regimes. We speculated that this could be a manifestation of the sudden change in the active regions dynamics, caused by the dynamic disconnection of sunspots from their magnetic roots as prop...

The usual conclusion in the literature is that sunspots reduce welfare because of the agents’ risk aversion. However, if sunspots can lead to escape from an inferior steady state (poverty trap), this conclusion does not necessarily hold. Escaping trajectories can have much higher welfare than those remaining in the poverty trap. The ex—post welfare effect can be positive for initial conditions ...