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Onset of the Magnetic Explosion in Solar Flares and Coronal Mass EjectionsWe present observations of the magnetic field configuration and its transformation in six solar eruptive events that show good agreement with the Hirayama-Shibata model for eruptive flares. The observations arc X-ray images from the Yohkoh Soft X-ray Telescope (SXT) and magnetograms from Kitt Peak National Solar Observatory, interpreted together with the 1-8 Angstrom X-ray flux observed by GOES. The observations show: 1. Each event is a magnetic explosion that occurs in an initially closed magnetic bipole in which the core field is sheared and twisted in the shape of a sigmoid, having an oppositely curved elbow on each end. The arms of the opposite elbows are sheared past each other so that they overlap and are crossed low above the neutral line in the middle of the bipole. 2. Although four of the explosions arc ejective (blow open the bipole) and two are confined (arc arrested within the closed bipole), all six begin the same way. In the SXT iniages, the explosion begins with brightening and expansion of the two elbows together with the appearance of short bright sheared loops low over the neutral line under the crossed arms and, rising up from the crossed arms, long strands connecting the far ends of the elbows. 3. All six events arc single-bipole events in that during the onset and early development of the explosion they show no evidence for reconnection between the exploding bipole and any surrounding magnetic fields. We conclude that in each of our events the magnetic explosion was unleashed by runaway tether-cutting via implosive/explosive rcconnection in the middle of the sigmoid, as in the Hirayama-Shibata model. The similarity of the onsets of the two confined explosions to the onsets of the four ejective explosions and their agreement with the model indicate that runaway reconnection inside a sheared core field can begin whether or not the overlying fields (the envelope field and contiguous fields that press down on the envelope) allow the explosion to be ejective. We consider the implications ofthis for the unleashing of magnetic explosions in field configurations composed of to or more impacted bipoles.
Document ID
20000108798
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Moore, R. L.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Sterling, A. C.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Hudson, H.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Lemen, J. R.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Rose, M. Franklin
Date Acquired
August 19, 2013
Publication Date
January 1, 2000
Subject Category
Solar Physics
Meeting Information
Meeting: UVCS/SOHO 2000 Science Meeting
Location: Northeast Harbor, ME
Country: United States
Start Date: September 27, 2000
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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