WORKING SURFACES IN RADIATIVE, NON-TOP HAT JETS

Most models of radiative jets have been computed for the special case of a top hat initial cross section. This paper discusses the dynamics of both leading and internal working surfaces in jets with more genera l initial cross sections, based on both an analytic, ''thin shell'' mo del, and on a full numerical simulation. We find that a non-top hat cr oss section for the jet ram pressure first leads to a strong curvature of the working surface shocks, and at longer timescales to the format ion of a warm, dense ''nose cone''. These results have interesting imp lications for comparisons between radiative jet models and observation s of Herbig-Haro objects.