A STRONG LIMITATION ON THE RAPIDITY OF FLUX-PILE-UP RECONNECTION

The reconnection rate which can be achieved in the steady-state flux-p ile-up regime is severely limited by the gas pressure of the plasma. U sing the family of solutions obtained previously by Priest and Forbes, we show that the Alfven Mach number of the plasma flowing towards the reconnection site cannot exceed pi beta(e)/(8 ln R(me)), where beta(e ) and R(me) are the plasma beta and magnetic Reynolds numbers at large distance. This limit corresponds to a very weak flux-pile-up, and it is a factor of beta(e) slower than the maximum Petschek rate. Thus the maximum flux-pile-up reconnection rate in the corona is at least two orders of magnitude smaller than the rate implied by hare observations .