Stability of radiative shocks with time-dependent cooling

Abstract

Radiative shocks are known to be subject to overstable oscillations in which the position of the shock front relative to the driving "piston" varies as a function of time. Various linear and nonlinear calculations have examined the properties of the instability for power-law cooling functions. However, the cooling functions appropriate to interstellar shock waves are history dependent: simple power-law approximations are not valid. In this work, a full evolutionary calculation of the ion abundances and radiative cooling is incorporated into an accurate one-dimensional gasdynamics calculation. It is found that radiative shocks are unstable for velocities in excess of ≡140 km s<SUP>-1</SUP>.