  We investigate the driving mechanism of outflows and jets in star formation
process using resistive MHD nested grid simulations. We found two distinct
flows in the collapsing cloud core: Low-velocity outflows (sim 5 km/s) with a
wide opening angle, driven from the first adiabatic core, and high-velocity
jets (sim 50 km/s) with good collimation, driven from the protostar.
High-velocity jets are enclosed by low-velocity outflow. The difference in the
degree of collimation between the two flows is caused by the strength of the
magnetic field and configuration of the magnetic field lines. The magnetic
field around an adiabatic core is strong and has an hourglass configuration.
Therefore, the low-velocity outflow from the adiabatic core are driven mainly
by the magnetocentrifugal mechanism and guided by the hourglass-like field
lines. In contrast, the magnetic field around the protostar is weak and has a
straight configuration owing to Ohmic dissipation in the high-density gas
region. Therefore, high-velocity jet from the protostar are driven mainly by
the magnetic pressure gradient force and guided by straight field lines.
Differing depth of the gravitational potential between the adiabatic core and
the protostar cause the difference of the flow speed. Low-velocity outflows
correspond to the observed molecular outflows, while high-velocity jets
correspond to the observed optical jets. We suggest that the protostellar
outflow and the jet are driven by different cores (the first adiabatic core and
protostar), rather than that the outflow being entrained by the jet.
