1 research outputs found
Formation of protostellar jets - effects of magnetic diffusion
We investigate the evolution of a disk wind into a collimated jet under the
influence of magnetic diffusivity, assuming that the turbulent pattern in the
disk will also enter the disk corona and the jet. Using the ZEUS-3D code in the
axisymmetry option we solve the time-dependent resistive MHD equations for a
model setup of a central star surrounded by an accretion disk. We find that the
diffusive jets propagate slower into the ambient medium. Close to the star we
find that a quasi stationary state evolves after several hundred (weak
diffusion) or thousand (strong diffusion) disk rotations. Magnetic diffusivity
affects the protostellar jet structure as follows. The jet poloidal magnetic
field becomes de-collimated. The jet velocity increases with increasing
diffusivity, while the degree of collimation for the hydrodynamic flow remains
more or less the same. We suggest that the mass flux is a proper tracer for the
degree of jet collimation and find indications of a critical value for the
magnetic diffusivity above which the jet collimation is only weak.Comment: 16 pages, 12 figs, accepted by Astron. and Astrop