A SELF-CONSISTENT MODEL FOR THE PARTICLES AND FIELDS UPSTREAM OF AN OUTGASSING COMET .2. A TIME-DEPENDENT DESCRIPTION

In a previous paper [Flammer et al., 1991], we determined the global variation of the magnetic field and solar wind flow parameters in the unshocked region upstream of an outgassing comet using a kinetic treatment for the cometary ions. Two different assumptions were made concerning the cometary ion distribution function: the pickup cometary ions formed either a velocity space gyrotropic ring distribution or a velocity space isotropic shell distribution in the solar wind frame of reference. In the present paper we consider the general case wherein the newly picked up ions are elastically pitch angle scattered from the initial ring distribution to a shell with some characteristic time scale-tau. Using theoretically determined parameters which reflect the conditions expected at comet Kopff (a typical short-period comet and a possible target for the CRAF/Cassini mission) for various heliocentric distances, we determine how the pitch angle scattering rate affects the global morphology.