Oblique magnetohydrodynamic shock waves in molecular clouds

Abstract

The structure of oblique steady plane-parallel radiative reacting C-type shocks in diffuse molecular clouds is examined. Numerical models are presented for typical parameters: n(H2) = 20/cu cm, n(H) = 10/cu cm, and v(s) = 10 km/s. C-type shock structure is weakly dependent on the angle (theta) between the upstream magnetic field B0 and the direction of shock propagation. For typical field strengths there is a critical angle below which the neutral flow must have at least one critical point (implying that the shock must be either transonic C-type or J-type), although in general this angle need not exist. Models differing only in the component of B0 parallel to the direction of shock propagation (i.e., having identical transverse components of B0) can have markedly different hydrodynamic structures. The column densities of most shock-produced species vary only mildly with theta between 90 and 40 deg when either B0 or B0 sin theta are held constant.