Electrodynamic forces in stellar formation

Due to dynamo action of a rotating collapsing protostellar cloud in an ambient interstellar magnetic field, electrodynamic forces are created. Assuming: 1) quasi-equilibrium (i.e. slow collapse) and 2) appreciable plasma slip relative to the rotating neutrals (i.e. low ionization with the ambipolar diffusion time smaller than the rotation period), we study the created electrodynamic forces for a range of protostellar parameters, in particular, as a function of the ambient magnetic field and the radius, mass angular velocity and temperature of the protostellar cloud. In general we find that (pinching) electrodynamic forces can be as important as gravitational forces (or even dominant in certain stages of the star formation process). (author)