On Internal and External Alignment of Dust Grains in Protostellar Environments

We study the physical processes inducing alignment of grain axis maximum inertia moment with angular momentum (${\bf J}$, i.e., internal alignment) and ${\bf J}$ magnetic field (i.e., external very large grains (VLGs, radius $a>10\mu$m) using framework based on radiative torques (RATs) mechanical (METs). derive analytical formulae for critical sizes alignment, assuming that are aligned at both low$-J$ high$-J$ attractors by RATs For protostellar cores, we find super-Barnett relaxation can induce efficient VLGs iron inclusions In contrast, inelastic be made any composition. have ($B-$RAT) or METs ($B-$ MET), enabling dust polarization as a reliable tracer fields in such dense regions. Still, without along radiation direction ($k-$RAT) gas flow ($v-$MET). disks, outer disk thanks to spinup METs, but is inefficient. low-J $k-$RAT ($v-$MET) likely $B-$RAT ($B-$MET) alignment. Grain appears more important than disks.