MHD Simulations of Dense Core Collision

We investigated the effect of magnetic fields on the collision process between dense molecular cores. We performed three-dimensional magnetohydrodynamic simulations of collisions between two self-gravitating cores using the Enzo adaptive mesh refinement code. The core was modeled as a stable isothermal Bonnor–Ebert (BE) sphere immersed in uniform magnetic fields. Collisions were characterized by the offset parameter b , Mach number of the initial core  , magnetic field strength B 0 , and angle θ between the initial magnetic field and collision axis. For head-on ( b = 0) collisions, one protostar was formed in the compressed layer. The higher the magnetic field strength, the lower the accretion rate. For models with b = 0 and θ = 90°, the accretion rate was more dependent on the initial magnetic field strength compared with b = 0 and θ = 0° models. For off-center ( b = 1) collisions, the higher specific angular momentum increased; therefore, the gas motion was complicated. In models with b = 1 and  = 1 , the number of protostars and gas motion highly depended on B 0 and θ . For models with b = 1 and  = 3 , no significant shock-compressed layer was formed and star formation was not triggered.