A TWISTED FLUX ROPE AS THE MAGNETIC STRUCTURE OF A FILAMENT IN ACTIVE REGION 10953 OBSERVED BY HINODE

The presence of twisted flux ropes (TFRs) in pre-eruptive/flaring magnetic configurations is of main interest for our understanding of the structure and dynamics of the solar corona. On the one hand, their presence is a key ingredient in several theoretical models for the magnetic support of material in filaments, or triggering of coronal mass ejections as well as the emergence of structures from the convection zone into the corona. On the other hand, several observations have shown the presence of twist and shear during eruptive and flaring phases of eruptive phenomena. In this paper, we consider the determination of the magnetic structure of active region (AR) 10953 observed by Hinode and reconstructed using our two nonlinear force-free models. We show that the reconstructed magnetic configurations exhibit a TFR along the southern part of the neutral line. Moreover, the location of the magnetic dips within the TFR agrees within a good level of accuracy with the H alpha images taken by SMART and the vertically integrated current density recovers the main structure present in Hinode/XRT images. The free magnetic energy is also found to be large enough to power the two C-class flares of the following days. We finally compare our results with those of Su et al. who proposed an interesting model of the same AR in which a TFR is inserted at the same location using the flux rope insertion method.