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Astron. Astrophys. 323, 593-598 (1997)

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Three-dimensional numerical study of converging flux events

J. Dreher 1, G.T. Birk 2 and T. Neukirch 3

1 Theoretische Physik IV, Ruhr-Universität Bochum, D-44780 Bochum, Germany
2 Institut für Astronomie und Astrophysik, Ludwig-Maximilians-Universität München, D-81679 München, Germany
3 School of Mathematical and Computational Sciences, University of St. Andrews, St. Andrews KY16 9SS, Fife, Scotland, UK

Received 30 May 1996 / Accepted 30 July 1996

Abstract

The first self-consistent three-dimensional magnetohydrodynamical simulations of converging magnetic flux events associated with the formation of coronal X-ray bright points are presented. The initial magnetic field results from two magnetic dipoles located below the photosphere at positions [FORMULA] and [FORMULA], respectively, and an additional horizontal magnetic field parallel to the line [FORMULA]. Both dipole moments are vertical and have equal magnitude but opposite orientation. During the dynamical evolution, a prescribed photospheric convection pattern causes the magnetic dipole-like structures to approach one another. In the early phase of the evolution a current sheet forms in the central region above the polarity inversion line. When the current density exceeds a critical value, anomalous resistivity due to microturbulence is assumed to break the ideal Ohm's law. As a consequence, magnetic reconnection sets in and results in a jet-like plasma flow. The localized plasma heating associated with the reconnection process might account for the flaring of tiny filaments within bright point structures.

Key words: solar corona – X-ray bright points – solar magnetic fields – MHD simulations – plasmas

Send offprint requests to: J. Dreher

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© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998

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