Observations from SDO, hinode, and stereo of a twisting and writhing start to a solar-filament-eruption cascade

Abstract

We analyze data from SDO (AIA, HMI), Hinode (SOT, XRT, EIS), and STEREO (EUVI) of a solar eruption sequence of 2011 June 1 near 16:00 UT, with an emphasis on the early evolution toward eruption. Ultimately, the sequence consisted of three emission bursts and two filament ejections. SDO/AIA 304 Å images show absorbing-material strands initially in close proximity which over 20 minutes form a twisted structure, presumably a flux rope with 1029 erg of free energy that triggers the resulting evolution. A jump in the filament/flux rope's displacement (average velocity 20 km s -1) and the first burst of emission accompanies the flux-rope formation. After 20 more minutes, the flux rope/filament kinks and writhes, followed by a semi-steady state where the flux rope/filament rises at (5 km s-1) for 10 minutes. Then the writhed flux rope/filament again becomes MHD unstable and violently erupts, along with rapid (50 km s -1) ejection of the filament and the second burst of emission. That ejection removed a field that had been restraining a second filament, which subsequently erupts as the second filament ejection accompanied by the third (final) burst of emission. Magnetograms from SDO/HMI and Hinode/SOT, and other data, reveal several possible causes for initiating the flux-rope-building reconnection, but we are not able to say which is dominant. Our observations are consistent with magnetic reconnection initiating the first burst and the flux-rope formation, with MHD processes initiating the further dynamics. Both filament ejections are consistent with the standard model for solar eruptions. © 2012. The American Astronomical Society. All rights reserved..