Dependence on Cooling Exponent

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 alpha (where the cooling rate is proportional to T**alpha). Note that the oscillations do not damp for alpha=0.5 (appropriate to bremstrahlung cooling), and even at alpha=0.75 high overtones are not completely damped.

Return to the Radiative Shocks page.