Speaker
Description
While recent observations of young protostellar disks have revealed much about their structure, their formation process from molecular cloud cores and subsequent evolution remains relatively poorly understood. In particular, the role of the magnetic field in regulating the angular momentum budget of the system is a central issue. In this talk, zoom-in simulations from a turbulent interstellar medium to protostars are presented, with a spatial range spanning more than 10 orders of magnitude. Using a newly developed implementation of non-ideal magnetohydrodynamics (MHD) for the moving-mesh code AREPO, we compare models without magnetic fields, with ideal MHD and finally including ambipolar diffusion. While disks of several 10s of astronomical units readily form without magnetic fields, ideal MHD strongly suppresses disk formation through magnetic braking and outflows. Non-ideal MHD does in a subset of cases lead to disk formation, but these disks are distinct from those without magnetic fields in size and structure. We show that where comparison can be made, our results are consistent with earlier studies of isolated cloud core collapse. We conclude that non-ideal MHD effects are prominent in the disk formation process even when fully self-consistent turbulent initial conditions are used, and their importance is not limited to idealized collapse scenarios. As such, both realistic initial conditions and the use of an appropriate magnetic field model are crucial in modeling the formation of protostellar disks. Finally, the effects of radiative transfer on disk structure and the impact of magnetic fields in the formation of multiples are briefly discussed.
| Category | Theory and simulations of disk formation |
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