NUMERICAL EXPERIMENTS OF WAVE-LIKE PHENOMENA CAUSED BY THE DISRUPTION OF AN UNSTABLE MAGNETIC CONFIGURATION

Abstract

The origin of the Moreton wave observed in the chromosphere and the EIT wave observed in the corona during the eruption remains an active research subject. We investigate numerically in this work the evolutionary features of the magnetic configuration that includes a current-carrying flux rope, which is used to model the filament, after the loss of equilibrium in the system takes place in a catastrophic fashion. Rapid motions of the flux rope following the catastrophe invoke the velocity vortices behind the rope, and may also invoke slow-and fast-mode shocks in front of the rope. The velocity vortices at each side of the flux rope propagate roughly horizontally away from the area where they are produced, and both shocks expand toward the flank of the flux rope. The fast shock may eventually reach the bottom boundary and produce two echoes moving back into the corona, but the slow one and the vortices totally decay somewhere in the lower corona before arriving of the bottom boundary. The interaction of the fast shock with the boundary leads to disturbance that accounts for the Moreton wave observed in Ha, and the disturbance in the corona caused by the slow shock and the velocity vortices should account for the EIT wave whose speed is about 40% that of the Moreton wave. The implication of these results to the observed correlation of the type II radio burst to the fast-and the slow-mode shocks and that of EIT waves to coronal mass ejections and flares has also been discussed.