ar X iv : a st ro - p h / 05 07 66 1 v 1 2 8 Ju l 2 00 5 Eruption of a kink - unstable filament in Active Region NOAA 10696

We present rapid-cadence Transition Region And Coronal Explorer (TRACE) observations which show evidence of a filament eruption from active region NOAA 10696, accompanied by an X2.5 flare, on 2004 November 10. The eruptive filament, which manifests as a fast coronal mass ejection some minutes later, rises as a kinking structure with an apparently exponential growth of height within TRACE’s field of view. We compare the characteristics of this filament eruption with MHD numerical simulations of a kink-unstable magnetic flux rope, finding excellent qualitative agreement. We suggest that, while tether-weakening by breakout-like quadrupolar reconnection may be the release mechanism for the previously confined flux rope, the driver of the expansion is most likely the MHD helical kink instability. Subject headings: MHD — Sun: activity — Sun: filaments — instabilities — Sun: magnetic fields Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Surrey, RH5 6NT, U.K. [email protected], [email protected], [email protected] Observatoire de Paris, LESIA, FRE 2461 (CNRS), F-92195 Meudon-Principal Cedex, France [email protected] Konkoly Observatory, P.O. Box 67, H-1525 Budapest, Hungary Astrophysikalisches Institut Potsdam, 14482 Potsdam, Germany [email protected]