A twisted flux rope model for coronal mass ejections and two-ribbon flares

We present a new approach to the theory of large-scale solar eruptive pheno mena such as coronal mass ejections and two-ribbon flares, in which twisted flux tubes play a crucial role. We show that it is possible to create a hi ghly nonlinear three-dimensional force-free configuration consisting of a t wisted magnetic flux rope representing the magnetic structure of a prominen ce (surrounded by an overlaying, almost potential, arcade) and exhibiting a n S-shaped structure, as observed in soft X-ray sigmoid structures. We also show that this magnetic configuration cannot stay in equilibrium and that a considerable amount of magnetic energy is released during its disruption. Unlike most previous models, the amount of magnetic energy stored in the c onfiguration prior to its disruption is so large that it may become compara ble to the energy of the open field.