Protostellar Disk and Star Cluster Formation With Realistic Feedback and Non-Ideal Magnetohydrodynamics
Nina Filippova, University of Texas at Austin
Protostellar disks are expected to form early during the star formation process due to conservation of angular momentum throughout the gravitational collapse of dense clumps of gas and dust. These disks funnel mass to the growing protostar as well as provide the raw material for subsequent planet formation. Recent surveys by the Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) observing dust continuum emission have measured typical disk radii of about 30-45 AU around hundreds of young protostars. Theoretical challenges in understanding how protostellar disks can even form, however, result from observations that angular momentum cannot be perfectly conserved. Magnetic fields, which are typically observed to be dynamically significant in star-forming regions, can help transport angular momentum out of the disk and collapsing envelope, but may be too efficient in the limit of ideal magnetohydrodynamics (MHD; in which the gas and magnetic field dynamics are well-coupled). In this limit, both theory and numerical simulations show that disk formation is strongly suppressed even under moderate magnetic field strengths.
Molecular clouds in which stars form are only partially ionized, however, and considering non-ideal MHD effects (Ohmic resistivity, ambipolar diffusion, and the Hall effect) may help resolve the magnetic braking catastrophe. We present the resulting disk characteristics from a suite of numerical calculations following the collapse of a turbulent, magnetized 50 solar-mass clump down to the formation of stellar clusters and disks using the quasi-Lagrangian Meshless Finite Mass (MFM) fluid solver in the 3-D radiation+gravity MHD code GIZMO, with additional modules for protostellar feedback (such as radiation and protostellar jets) developed within the STARFORGE numerical framework. These simulations aim to investigate the effects of including non-ideal MHD and realistic protostellar feedback on disk formation and evolution within the context of star cluster (rather than single-star) formation.
Abstract Author(s): Nina Filippova, Stella S.R. Offner, the STARFORGE team