Astron. Astrophys. 331, 1078-1086 (1998)

Slow and fast magnetic reconnection

I. Role of radiative cooling

A.V. Oreshina and B.V. Somov

Solar Physics Department, Astronomical Institute, Moscow State University, Universitetskii Prospekt 13, Moscow 119899, Russia (e-mail: somov@sai.msu.su)

Received 30 July 1997 / Accepted 13 November 1997

Abstract

New model of a magnetically non-neutral reconnecting current sheet (RCS) in the solar corona is developed to investigate different structures of the RCS and different regimes of reconnection corresponding to these structures. In this paper (Paper 1) we formulate the mathematical problem and consider mainly the solutions that demonstrate an influence of the radiative cooling on the RCS structure and reconnection rate. The solution for low temperatures () of plasma in the RCS, when heat conduction is not important, shows that the radiative losses of energy make the current sheet be thinner, denser, and colder; the velocity of plasma outflows from it slows down. The transition from the slow regime of reconnection (with the magnetic field configuration of O-type in a central region of the RCS) to the fast one (with the configuration of X-type) is realized at larger rates of reconnection as compared with the case where radiation is not taken into account. This result makes more probable the formation of solar prominences via slow magnetic reconnection in the RCS with magnetic island in the central region of current sheet. The transition from slow reconnection to fast one presumably means destabilization of a quiescent prominence and triggering a flare.

Key words: magnetohydrodynamics Sun: corona Sun: magnetic fields Sun: prominences

© European Southern Observatory (ESO) 1998

Online publication: March 3, 1998
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