Drift and Deformation of a Flux Rope Footpoint Observed during an Eruptive Flare

In this contribution we present an analysis of EUV (SDO/AIA), X-ray (Hinode/XRT) and H-alpha (KSO, University of Graz, Austria) imaging observations of an M-class eruptive flare of 2015 November, 4 that showed long-distance drift of the eruptive flux rope foot-points. Before the flare we observed an H-alpha filament which activated due to flux cancellation observed close to its central part. The tether-cutting reconnection, occurring at the beginning of the flare, involved the filament threads and built up and enlarged flux rope spanning over the H-alpha filament. Hot sigmoidal loop structure of this enlarged flux rope was observed in SDO/AIA 131A and Hinode/XRT Be_med filters. Its positive foot-point was rooted in a small hook that formed at the end of the flare ribbon in early impulsive phase of the flare. Subsequently, the hot loops started to slip away form that small hook until it disappeared and the ribbon in positive polarity was elongated by more than 40 arcseconds via slipping of the loops. When elongating of the ribbon stopped, a new large hook formed at its end. Formation of a large hook was associated with eruption of hot and twisted loops rooted at this hook. Also, after the eruption of hot loops the deformation of the ribbon hook still continued. At first it was observed expanding and later contracting. We interpret our observations in the framework of the recent 3D extensions to the standard solar flare model, which predict the drift and deformation of the flux rope foot-points.