Modeling Repeatedly Flaring $δ$ Sunspots

Abstract

Active regions (AR) appearing on the surface of the Sun are classified into $α$, $β$, $γ$, and $δ$ by the rules of the Mount Wilson Observatory, California on the basis of their topological complexity. Amongst these, the $δ$-sunspots are known to be super-active and produce the most X-ray flares. Here, we present results from a simulation of the Sun by mimicking the upper layers and the corona, but starting at a more primitive stage than any earlier treatment. We find that this initial state consisting of only a thin sub-photospheric magnetic sheet breaks into multiple flux-tubes which evolve into a colliding-merging system of spots of opposite polarity upon surface emergence, similar to those often seen on the Sun. The simulation goes on to produce many exotic $δ$-sunspot associated phenomena: repeated flaring in the range of typical solar flare energy release and ejective helical flux ropes with embedded cool-dense plasma filaments resembling solar coronal mass ejections.

Minor changes consistent with Phys Rev Lett version