Observed protostellar outflows exhibit a variety of asymmetrical features,
including remarkable unipolar outflows and bending outflows. Revealing the
formation and early evolution of such asymmetrical protostellar outflows,
especially the unipolar outflows, is essential for a better understanding of
the star and planet formation because they can dramatically change the mass
accretion and angular momentum transport to the protostars and protoplanetary
disks. Here, we perform the three-dimensional non-ideal magnetohydrodynamics
simulations to investigate the formation and early evolution of the
asymmetrical protostellar outflows in magnetized turbulent isolated molecular
cloud cores. We find, for the first time to our knowledge, that the unipolar
outflow forms even in the single low-mass protostellar system. The results show
that the unipolar outflow is driven in the weakly magnetized cloud cores with
the dimensionless mass-to-flux ratios of μ=8 and 16. Furthermore, we find
the protostellar rocket effect of the unipolar outflow, which is
similar to the launch and propulsion of a rocket. The unipolar outflow ejects
the protostellar system from the central dense region to the outer region of
the parent cloud core, and the ram pressure caused by its ejection suppresses
the driving of additional new outflows. In contrast, the bending bipolar
outflow is driven in the moderately magnetized cloud core with μ=4. The
ratio of the magnetic to turbulent energies of a parent cloud core may play a
key role in the formation of asymmetrical protostellar outflows.Comment: 24 pages, 6 figures, accepted for publication in Ap