Electric current filamentation at a nonpotential magnetic nullpoint due to pressure perturbation 

Petr Jelinek Submitted: 20151014 00:52
An increase of electric current densities due to filamentation is an important process in any flare. We show that the pressure perturbation, followed by an entropy wave, triggers such a filamentation in the nonpotential magnetic nullpoint. In the twodimensional (2D), nonpotential magnetic nullpoint, we generate the entropy wave by a negative or positive pressure pulse that is launched initially. Then, we study its evolution under the influence of the gravity field. We solve the full set of 2D time dependent, ideal magnetohydrodynamic equations numerically, making use of the FLASH code. The negative pulse leads to an entropy wave with a plasma density greater than in the ambient atmosphere and thus this wave falls down in the solar atmosphere, attracted by the gravity force. In the case of the positive pressure pulse, the plasma becomes evacuated and the entropy wave propagates upward. However, in both cases, owing to the Rayleigh?Taylor instability, the electric current in a nonpotential magnetic nullpoint is rapidly filamented and at some locations the electric current density is strongly enhanced in comparison to its initial value. Using numerical simulations, we find that entropy waves initiated either by positive or negative pulses result in an increase of electric current densities close to the magnetic nullpoint and thus the energy accumulated here can be released as nanoflares or even flares.
Authors: P. Jelinek, M. Karlický, K. Murawski
Projects: None

Publication Status: ApJ 812, 105, 2015
Last Modified: 20151015 07:27


