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A. C. Sterling (NASA/MSFC/NSSTC/JAXA/ISAS/UAT/UCL), R. L. Moore (NASA/MSFC/NSSTC)
We observe two near-limb solar filament eruptions, one of 2000 February~26 and the other of 2002 January~4, using 195~Å\ Fe~{\sc xii}\ images from SOHO/EIT and magnetograms from SOHO/MDI\@. For the earlier event we also use soft X-ray data from Yohkoh/SXT, and hard X-ray data from Yohkoh/HXT and CGRO/BATSE\@. Both events occur in quadrupolar magnetic regions, and both have coronal features belonging to the same magnetic-cavity-structures as the filaments. In both cases the cavity and filament have a slow-rise phase of ~ 10~km~s-1 prior to eruption, followed by a fast-rise phase of ~100~km~s-1 during eruption. We estimate both filaments and both cavities to contain masses of ~ 1014-15~g and ~1015-16~g, respectively. We consider two specific magnetic-reconnection-based models for eruption onset, the ``tether cutting'' and the ``breakout'' models. In the earlier event SXT images show an intensity increase during the 12-minute interval over which the fast phase begins, consistent with tether-cutting. Substantial hard X-rays, however, do not occur until after fast eruption is underway, which provides a constraint on the tether-cutting model. Also around the time fast eruption begins there are brightenings and topological changes in the corona indicative of high-altitude reconnection, consistent with breakout. In both eruptions, however, fast rise onset occurs while cavity-related coronal loops are still evolving from ``closed'' to ``open,'' providing constraints on the breakout model. Therefore our findings are consistent with aspects of both models, but we cannot say which, if either, mechanism triggered the fast phase. We have also found specific constraints that either model, or any other eruption-onset model, must satisfy if correct. NASA supported this work through SR&T and SEC GI grants.
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.