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Title: ELECTRIC CURRENT FILAMENTATION AT A NON-POTENTIAL MAGNETIC NULL-POINT DUE TO PRESSURE PERTURBATION

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 non-potential magnetic null-point. In the two-dimensional (2D), non-potential magnetic null-point, 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 non-potential magnetic null-point 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 currentmore » densities close to the magnetic null-point and thus the energy accumulated here can be released as nanoflares or even flares.« less
Authors:
 [1] ;  [2] ;  [3]
  1. University of South Bohemia, Faculty of Science, Institute of Physics and Biophysics, Branišovská 10, CZ-37005 České Budějovice (Czech Republic)
  2. Academy of Sciences of the Czech Republic, v. v. i., Astronomical Institute, Fričova 258, CZ-25165 Ondřejov (Czech Republic)
  3. Maria Curie-Skłodowska University, Institute of Physics, Group of Astrophysics, Radziszewskiego 10, PL-20031 Lublin (Poland)
Publication Date:
OSTI Identifier:
22518790
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 812; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; DENSITY; DISTURBANCES; ELECTRIC CURRENTS; ENTROPY; GRAVITATION; MAGNETOHYDRODYNAMICS; PLASMA DENSITY; POTENTIALS; RAYLEIGH-TAYLOR INSTABILITY; SOLAR ATMOSPHERE; SUN; TIME DEPENDENCE; TWO-DIMENSIONAL SYSTEMS