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Disruption of coronal magnetic field arcadesThe ideal and resistive properties of isolated large-scale coronal magnetic arcades are studied using axisymmetric solutions of the time-dependent magnetohydrodynamic (MHD) equations in spherical geometry. We examine how flares and coronal mass ejections may be initiated by sudden disruptions of the magnetic field. The evolution of coronal arcades in response to applied shearing photospheric flows indicates that disruptive behavior can occur beyond a critical shear. The disruption can be traced to ideal MHD magnetic nonequilibrium. The magnetic field expands outward in a process that opens the field lines and produces a tangential discontinuity in the magnetic field. In the presence of plasma resistivity, the resulting current sheet is the site of rapid reconnection, leading to an impulsive release of magnetic energy, fast flows, and the ejection of a plasmoid. We relate these results to previous studies of force-free fields and to the properties of the open-field configuration. We show that the field lines in an arcade are forced open when the magnetic energy approaches (but is still below) the open-field energy, creating a partially open field in which most of the field lines extend away from the solar surface. Preliminary application of this model to helmet streamers indicates that it is relevant to the initiation of coronal mass ejections.
Document ID
19950029330
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Mikic, Zoran
(Science Appl. Int. Corp. San Diego, CA, United States)
Linker, Jon A.
(Univ. of California at San Diego, La Jolla, CA United States)
Date Acquired
August 16, 2013
Publication Date
August 1, 1994
Publication Information
Publication: The Astrophysical Journal
Volume: 430
Issue: 2 pt
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A60929
Funding Number(s)
CONTRACT_GRANT: NAG5-1492
CONTRACT_GRANT: NSF ATM-92-96165
CONTRACT_GRANT: NASW-4728
Distribution Limits
Public
Copyright
Other

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