EVOLUTION OF KELVIN-HELMHOLTZ INSTABILITIES IN RADIATIVE JETS .2. SHOCK STRUCTURE AND ENTRAINMENT PROPERTIES

We present the results of a 2-D numerical analysis of the stability of radiative supersonic cylindrical jets against Kelvin-Helmholtz instab ilities. The numerical scheme employed is a PPM-type code, the boundar y conditions are periodic on the longitudinal direction, i.e we adopt a temporal approach; the interface between the jet and the ambient med ium is modeled by a smooth velocity and density transition. The equili brium configuration is perturbed by a superposition of axisymmetric lo ngitudinally periodic transverse velocity disturbances. We discuss the physical details of the temporal evolution of the instability when af fected by non-equilibrium radiative losses in comparison with the adia batic case for a perfect gas equation of state. We find that radiation strongly affects the instability evolution by limiting the mixing and momentum transfer processes between the jet and the ambient medium, d epending mainly on the choice of the initial jet density. Our results are relevant for interpreting the phenomenology of YSO jets.