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Title: CURRENT SHEETS FORMATION IN TANGLED CORONAL MAGNETIC FIELDS

We investigate the dynamical evolution of magnetic fields in closed regions of solar and stellar coronae. To understand under which conditions current sheets form, we examine dissipative and ideal reduced magnetohydrodynamic models in Cartesian geometry, where two magnetic field components are present: the strong guide field B{sub 0}, extended along the axial direction, and the dynamical orthogonal field b. Magnetic field lines thread the system along the axial direction that spans the length L and are line-tied at the top and bottom plates. The magnetic field b initially has only large scales, with its gradient (current) length scale of the order of l{sub b}. We identify the magnetic intensity threshold b/B{sub 0} {approx} l{sub b}/L. For values of b below this threshold, field-line tension inhibits the formation of current sheets, while above the threshold they form quickly on fast ideal timescales. In the ideal case, above the magnetic threshold, we show that current sheets thickness decreases in time until it becomes smaller than the grid resolution, with the analyticity strip width {delta} decreasing at least exponentially, after which the simulations become underresolved.
Authors:
 [1] ;  [2]
  1. Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)
  2. Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)
Publication Date:
OSTI Identifier:
22140250
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 773; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; EVOLUTION; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; PLATES; RESOLUTION; SIMULATION; SOLAR CORONA; STELLAR CORONAE; SUN; THICKNESS; TOPOLOGY