MAGNETICALLY-AIDED EVOLUTION OF PROTOPLANETARY DISKS

We investigate the global evolution of a turbulent protoplanetary disk incorporating the effects of Maxwell stress due to a large-scale magn etic field permeating the disk. A magnetic field is produced continuou sly by an alpha Omega dynamo and the resultant Maxwell stress assists the viscous stress in p roviding the means for disk evolution. The mos t striking feature of magnetized disk evolution is the presence of the surface density bulge located in the ''magnetic gap'', the region of the disk where the degree of ionization is too low to allow for coupli ng between the magnetic field and the gas. The bulge persists for a t ime of the order of 10(5)-10(6) yr. The presence and persistence of th e surface density bulge may have important implications for the proces s of planet formation and the overall characteristics of resultant pla netary systems.