Magnetic reconnection and star formation in molecular clouds

We present a simple numerical model for the internal dynamics of a molecular cloud, based on the premise that a molecular cloud consists of a low-P plasma permeated by a spectrum of marginally non-linear Alfven waves. In such circumstances the gas is forced to be mostly in the form of high-density condensations or 'clumplets'. The model involves the dynamics of these dense clumplets of gas, threaded by field lines. We find that in general the random velocities of the clumplets lead to the intersection, and therefore to the reconnection, of field lines. In a 3D geometry this process appears to lead inevitably to the formation of closed loops of field, which are then able to annihilate. We conclude that we have hereby identified a process which results, throughout the cloud, in the steady generation of dense material which has been freed from the direct influence of the permeating magnetic field. It seems likely that this essentially field-free gas would be able to agglomerate within the cloud, and so initiate star formation.