Protoplanetary disk formation from the collapse of a prestellar core
  While it is generally accepted that the magnetic field and its non-ideal
effects play important roles during the stellar formation, simple models of
pure hydrodynamics and angular momentum conservation are still widely employed
in the studies of disk assemblage in the framework of the so-called
"alpha-disk" model due to their simplicity. There has only been a few efforts
trying to bridge the gap between a collapsing prestellar core and a developed
disk. The goal of the present work is to revisit the assemblage of the
protoplanetary disk (PPD), by performing 3D MHD simulations with ambipolar
diffusion and full radiative transfer. We follow the global evolution of the
PPD from the prestellar core collapse for 100 kyr, with resolution of one AU.
The formed disk is more realistic and is in agreement with recent observations
of disks around class-0 young stellar objects. The mass flux arriving onto the
disk and the radial mass accretion rate within the disk are measured and
compared to analytical self-similar models. The surface mass flux is very
centrally peaked, implying that most of the mass falling onto the star does not
transit through the mid-plane of the disk. The disk mid-plane is almost dead to
turbulence, whereas upper layers and the disk outer edge are very turbulent.
The snow-line is significantly further away than in a passive disk. We
developed a zoomed rerun technique to quickly obtain a reasonable disk that is
highly stratified, weakly magnetized inside, and strongly magnetized outside.
During the class-0 phase of PPD formation, the interaction between the disk and
the infalling envelope is important and ought not be neglected. Accretion onto
the star is found to mostly depend on dynamics of the collapsing envelope,
rather than the detailed disk structure.
