Understanding Stellar Multiplicity Through Disk Fragmentation and Pre-Stellar Core Evolution
Nina Filippova, University of Texas at Austin
Most stars form in systems containing multiple gravitationally bound stars, with the multiplicity fraction increasing with primary stellar mass. Theoretical mechanisms for multiple formation include fragmentation of dense filaments and cores formed during the gravitational contraction of turbulent molecular clouds, as well as fragmentation of the protostellar disk formed due to conservation of angular momentum in the natal cloud core. The dominant formation mechanism is still poorly constrained due to observational limitations. Numerical simulations can be used to trace the formation and dynamical evolution of multiple systems, with results compared to observed multiplicity statistics, to better understand the origin of multiple systems. We use the quasi-Lagrangian Meshless Finite Mass (MFM) fluid solver in the 3D radiation+gravity MHD code GIZMO, with additional modules for stellar feedback and dynamical evolution developed within the STARFORGE (STAR FORmation in Gaseous Environments) numerical framework, to model mechanisms for the formation of multiple systems. We model protostellar disk formation and evolution with realistic protostellar feedback and non-ideal magnetohydrodynamics (MHD) to address whether non-ideal MHD can overcome the “magnetic braking catastrophe” to produce disks large enough to gravitationally fragment into companion stars. We also trace the flow of gas onto stars in the STARFORGE simulation suite and compare the evolution of pre-stellar core gas properties prior to accretion, using machine learning (ML) techniques such as support vector machines (SVM) and neural networks to assist in predicting stellar multiplicity.