Shear-induced instability and arch filament eruption: A magnetohydrodynamic (MHD) numerical simulation
Abstract
We investigate, via a two-dimensional (nonplanar) MHD simulation, a situation wherein a bipolar magnetic field embedded in a stratified solar atmosphere (i.e., arch-filament-like structure) undergoes symmetrical shear motion at the footpoints. It was found that the vertical plasma flow velocities grow exponentially leading to a new type of global MHD-instability that could be characterized as a `Dynamic Shearing Instability', with a growth rate of about √8{ovV}Aa, where {ovV}A is the average Alfvén speed and a−1 is the characteristic length scale. The growth rate grows almost linearly until it reaches the same order of magnitude as the Alfvén speed. Then a nonlinear MHD instability occurs beyond this point. This simulation indicates the following physical consequences: the central loops are pinched by opposing Lorentz forces, and the outer closed loops stretch upward with the vertically-rising mass flow. This instability may apply to arch filament eruptions (AFE) and coronal mass ejections (CMEs).
- Publication:
-
Solar Physics
- Pub Date:
- August 1991
- DOI:
- 10.1007/BF00152653
- Bibcode:
- 1991SoPh..134..353W
- Keywords:
-
- Digital Simulation;
- Magnetohydrodynamic Stability;
- Mathematical Models;
- Solar Atmosphere;
- Solar Prominences;
- Magnetic Field Configurations;
- Solar Corona;
- Solar Magnetic Field;
- Time Dependence;
- Solar Physics;
- Mass Flow;
- Coronal Mass Ejection;
- Lorentz Force;
- Velocity Growth;
- Solar Atmosphere