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MHD Simulation of Chromospheric Evaporation in a Solar Flare Based on Magnetic Reconnection Model

Published online by Cambridge University Press:  25 May 2016

T. Yokoyama
Affiliation:
National Astronomical Observatory of Japan Mitaka, Tokyo, 181 Japan
K. Shibata
Affiliation:
National Astronomical Observatory of Japan Mitaka, Tokyo, 181 Japan

Extract

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Two-dimensional magnetohydrodynamic simulation of a solar flare is performed using a newly developed MHD code including nonlinear anisotropic heat conduction effect (Fig. 1; Yokoyama & Shibata 1997a). The numerical simulation starts with a vertical current sheet which is line-tied at one end to a dense chromosphere. The flare energy is released by the magnetic reconnection mechanism stimulated initially by the resistivity perturbation in the corona. The released thermal energy is transported into the chromosphere by heat conduction and drives chromospheric evaporation. Owing to the heat conduction effect, the adiabatic slow-mode MHD shocks emanated from the neutral point are dissociated into conduction fronts and isothermal shocks (Yokoyama & Shibata 1997b). Temperature and derived soft X-ray distributions are similar to the cusp-like structure of long-duration-event (LDE) flares observed by the soft X-ray telescope aboard Yohkoh satellite. On the other hand density and radio maps show a simple loop configuration which is consistent with the observation with Nobeyama Radio Heliograph. Two interesting new features are found. One is a pair of high density humps on the evaporated plasma loops formed at the collision site between the reconnection jet and the evaporation flow. The other is the loop-top blob behind the fast-mode MHD shock.

Type
Session 1: Plasma and Fresh Nucleosynthesis Phenomena
Copyright
Copyright © Kluwer 1998 

References

Yokoyama, T. and Shibata, K. (1997a) Two-Dimensional Magnetohydrodynamic Simulation of Chromospheric Evaporation in Solar Flare Based on Magnetic Reconnection Model, submitted to ApJ Letters.CrossRefGoogle Scholar
Yokoyama, T. and Shibata, K. (1997b) Magnetic Reconnection Coupled with Heat Conduction, Astrophys. J. , 474, L61.CrossRefGoogle Scholar