  We report the first three-dimensional radiation magnetohydrodynamic (RMHD)
simulations of protostellar collapse with and without Ohmic dissipation.We take
into account many physical processes required to study star formation
processes, including a realistic equation of state. We follow the evolution
from molecular cloud cores until protostellar cores are formed with
sufficiently high resolutions without introducing a sink particle. The physical
processes involved in the simulations and adopted numerical methods are
described in detail.We can calculate only about one year after the formation of
the protostellar cores with our direct three-dimensional RMHD simulations
because of the extremely short timescale in the deep interior of the formed
protostellar cores, but successfully describe the early phase of star formation
processes. The thermal evolution and the structure of the first and second
(protostellar) cores are consistent with previous one-dimensional simulations
using full radiation transfer, but differ considerably from preceding
multi-dimensional studies with the barotropic approximation. The protostellar
cores evolve virtually spherically symmetric in the ideal MHD models because of
efficient angular momentum transport by magnetic fields, but Ohmic dissipation
enables the formation of the circumstellar disks in the vicinity of the
protostellar cores as in previous MHD studies with the barotropic
approximation. The formed disks are still small (less than 0.35 AU) because we
simulate only the earliest evolution. We also confirm that two different types
of outflows are naturally launched by magnetic fields from the first cores and
protostellar cores in the resistive MHD models.
