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