On the role of current dissipation in the energization of coronal bright points

¹ Max-Planck-Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany
e-mail: buechner@mps.mpg.de
² Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA
e-mail: ao@how.gi.alaska.edu

Received: 12 February 2013
Accepted: 14 June 2013

Abstract

Aims. In the context of the contributions by DC dissipation to the energization of solar coronal X-ray and EUV bright points, we analyze the role of Joule heating in the formation of X-ray and EUV coronal bright points through current dissipation due to anomalous resistivity.

Methods. We utilized the improved resistive MHD simulation code MPSCORONA3D, which allows for investigating resistive effects within the corona over a wide range of Reynolds numbers, starting from the nearly ideal Spitzer value of resistivity and including various models of current-carrier velocity dependent resistivity, arising from the consideration of turbulence in microscopic theory.

Results. DC current dissipation contributes to the thermal energy increase in coronal bright point regions only under the assumption of an unrealistically low critical current-carrier velocity at which turbulent resistivity is switched on. For more realistic resistivity models, the corona is energized by plasma compression rather than by Joule heating due to the dissipation of direct currents.

Conclusions. Joule heating within the solar corona depends critically on the magnitude of the resistivity.