The responses of magnetically subcritical cores to shocks

Abstract

An ideal magnetohydrodynamics code with adaptive mesh refinement was used to investigate the interactions of fast-mode shocks with self-gravitating, isothermal cores with mass-to-flux ratios that are somewhat below the minimum value required for gravitational collapse. We find that shock focusing produces colliding flows along the field lines that generate very high densities, even for relatively weak shocks. Self-gravity plays only a minor role in determining the highest density that is reached, but it does play a role in the subsequent evolution. The densities at comparable times differ by a factor of a few for shocks initially propagating perpendicularly or obliquely to the magnetic field in the ambient medium. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.