Evolving force-free magnetic fields. III - States of nonequilibrium and the preflare stage

Abstract

view Abstract Citations (18) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evolving force-free magnetic fields. III - States of nonequilibrium and the preflare stage Low, B. C. Abstract The paper considers whether a neighboring magnetostatic equilibrium exists to allow a magnetic field initially in a force-free configuration to accommodate any imposed weak pressure. The following problem is treated. The foot points of the field are fixed and the plasma is frozen into the field lines under the approximation of infinite electrical conductivity. A weak pressure is introduced. It is determined infinitesimal plasma displacements exist to adjust the field lines to a new equilibrium without changing the field line connectivity. The analysis is carried out for the bipolar force-free fields forming one of two evolutionary sequences modeling the development of the preflare stage. It was found that for the force-free field corresponding to the quasi-static stage of evolution, the neighboring magnetostatic equilibrium always exists and the imposed gas pressure can be accommodated with a slight departure of the field from being exactly force free. Publication: The Astrophysical Journal Pub Date: July 1980 DOI: 10.1086/158118 Bibcode: 1980ApJ...239..377L Keywords: Force-Free Magnetic Fields; Magnetostatic Fields; Nonequilibrium Conditions; Plasma Equilibrium; Solar Flares; Solar Magnetic Field; Stellar Evolution; Gas Pressure; Lines Of Force; Low Pressure; Magnetohydrodynamics; Numerical Analysis; Solar Atmosphere; Solar Physics full text sources ADS |