Dependence on Mach Number
The following images display the space-time history of
the gas density in 1D simulations of interstellar radiative shocks.
Dark blue is the preshock supersonic gas flowing down from above,
light blue is the hot postshock gas that is radiatively cooling,
and red is the cold, dense gas that has radiated away most of its
thermal energy.
Initially steady state shocks are perturbed by "squeezing" the
postshock cooling region. The stability of the shock to such a
perturbation increases with decreasing Mach number.