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Disruption of coronal magnetic field arcades
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1994
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The study builds on prior work on force‑free fields and the characteristics of open‑field configurations. The authors investigate whether flares and coronal mass ejections can be triggered by sudden disruptions of coronal magnetic fields. They model isolated large‑scale coronal arcades with axisymmetric, time‑dependent MHD equations in spherical geometry to study ideal and resistive behavior. Simulations reveal that beyond a critical shear, arcades become unstable, opening field lines and forming a tangential discontinuity, and that resistivity creates a current sheet that undergoes rapid reconnection, releasing energy, driving fast flows, and ejecting a plasmoid, a process relevant to CME initiation. Published in The Astrophysical Journal, August 1994 (DOI 10.1086/174460).
view Abstract Citations (423) References (58) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Disruption of Coronal Magnetic Field Arcades Mikic, Zoran ; Linker, Jon A. Abstract The 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. Publication: The Astrophysical Journal Pub Date: August 1994 DOI: 10.1086/174460 Bibcode: 1994ApJ...430..898M Keywords: Hydrodynamic Equations; Magnetohydrodynamics; Solar Corona; Solar Flares; Solar Magnetic Field; Stellar Mass Ejection; Astronomical Models; Astrophysics; Current Sheets; Magnetic Field Configurations; Time Dependence; Astrophysics; MAGNETOHYDRODYNAMICS: MHD; SUN: CORONA; SUN: FLARES; SUN: MAGNETIC FIELDS full text sources ADS |