EDP Sciences
Free access
Issue
A&A
Volume 382, Number 2, February I 2002
Page(s) 639 - 649
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20011645


A&A 382, 639-649 (2002)
DOI: 10.1051/0004-6361:20011645

Physical consequences of the inclusion of anomalous resistivity in the dynamics of 2D magnetic reconnection

I. Roussev1, 2, K. Galsgaard3 and P. G. Judge1

1  High Altitude Observatory, NCAR, 3450 Mitchell Lane, Boulder, CO 80301, USA
    e-mail: judge@ucar.edu
2  Armagh Observatory, College Hill, Armagh, BT61 9DG, N. Ireland
3  University of St. Andrews, School of Mathematics and Statistics, North Haugh, St. Andrews, Fife, KY16 9SS, Scotland
    e-mail: klaus@mcs.st-and.ac.uk

(Received 14 August 2001 / Accepted 15 November 2001 )

Abstract
The aim of the present paper is to explore the role of anomalous resistivity on the dynamics of magnetic reconnection in a 2D environment of relevance to the solar transition region. We adopt an ad hoc but explicit form of the anomalous resistivity, motivated by a streaming instability, in which the resistivity jumps suddenly as the electron drift velocity exceeds some fraction of the mean electron thermal speed. Experiments have been conducted to investigate the impact of various critical speeds and arbitrary scaling constants of the resistivity level on the time-dependent evolution of the magnetic reconnection process. The specific threshold value is found to influence the dynamics of the reconnection, with higher values providing a localised on-off effect of patchy diffusion. For a given normalised value of the anomalous resistivity, the amount of Joule heating released scales inversely with the threshold value. The total energy release is found to be above the lower limit of "quiet" Sun nano-flares required to maintain a hot corona. The reconnection events discussed here may be important to the energy balance of the solar transition region and overlying corona, as already suggested in earlier work based on SUMER observations.


Key words: MHD -- Sun: atmosphere -- Sun: transition region -- Sun: magnetic fields

Offprint request: I. Roussev, ilr@ucar.edu




© ESO 2002