Radiative MHD Modeling of Flare-productive Sunspots

Shin Toriumi (ISAS/JAXA)

Observations revealed that the solar flares, especially the strongest events in history, emanate from complex-shaped sunspot regions. However, it has been extremely difficult to investigate the formation process of sunspots because we cannot optically observe the subsurface layer of the Sun, where magnetic fields rise and build up sunspots on the photosphere. In this study, for the first time, we succeed in simulating the entire process, in which a subsurface magnetic flux tube is elevated by the turbulent background convection and spontaneously forms complex sunspots. We find that the sunspots have a “delta” configuration (the most eruptive category of sunspots) with a strong magnetic shear and helical flux rope structure, all off which are consistent with the observations of flare-productive regions. In this talk, we discuss the key roles of turbulent convection in producing such violent sunspots.