New determinations of the critical velocities ...

Le Bourlot et al. (2002, MNRAS, in press) have computed a grid of models of C-type shocks.  The numerical results are available for preshock gas densities:

nH = 10³cm^-3, 10⁴cm^-3, 10⁵cm^-3, 10⁶cm^-3, 10⁷cm^-3