Dartmouth Events

Abstract: It has been observationally well established that the magnetic configurations most favorable for producing energetic solar flaring events reside in delta-spots, a class of sunspots defined as having opposite-polarity umbrae sharing a common penumbra. They are frequently characterized by extreme compactness and strong rotation. Numerous studies have shown that nearly all of the largest solar flares originate in delta-spots, making the understanding of these structures a fundamental step in predicting space weather. Despite their important influence on the space environment, surprisingly little is understood about the origin and behavior of delta-spots. In this talk, I present a systematic study of the behavior of emerging flux ropes to test a theoretical model for the formation of delta-spots: the kink instability of emerging flux ropes. We simulated the emergence of highly twisted, kink-unstable flux ropes from the solar interior into the corona, and we compared their properties at the solar surface to those of emerged weakly twisted, kink-stable flux ropes. We show that the surface manifestations of the emergence of highly twisted flux ropes closely match the observed properties of delta-spots, and we discuss the resulting implications for observations. Our results strongly support and extend previous theoretical work that suggested that the kink instability of emerging flux ropes is a promising candidate to explain delta-spot formation, as it reproduces their key characteristics very well.