The Wardle Instability in Interstellar Shocks: II. Gas Temperature and Line Emission

We have modeled the gas temperature structure in unstable C-type shocks and obtained predictions for the resultant CO and H2 rotational line emissions, using numerical simulations of the Wardle instability that were carried out by Stone (1997) and that have been described in a companion paper. We obtained results for the gas temperature distribution in -- and H2 and CO line emission from -- shocks of neutral Alfvenic Mach number 10 and velocity 20 or 40 km/sec in which the Wardle instability has saturated. Although the Wardle instability profoundly affects the density structure behind C-type shocks, most of the shock-excited molecular line emission is generated upstream of the region where the strongest effects of the instability are felt. Thus the Wardle instability has a relatively small effect upon the overall gas temperature distribution in -- and the emission line spectrum from -- C-type shocks, at least for the cases that we have considered.