RADIATION GASDYNAMICS OF PLANETARY-NEBULAE .5. HOT BUBBLE AND SLOW WIND DYNAMICS

This paper looks into various aspects brought to light by numerical wo rk on the generalized interacting winds model for planetary nebulae, F irst, a detailed comparison between radiative and non-radiative models is made, showing that one's naive expectations of the effects of radi ative heating and cooling are not always true, Secondly, we consider t he evolution of the slow wind after it has become ionized, It is found that the initial aspherical density distribution is smoothed out afte r ionization, thus requiring the aspherical nebula to be formed within the first few thousand years of PN evolution, Thirdly, the nature of the how in the hot bubble is investigated, Both one-and two-dimensiona l numerical models show strong signs of instabilities or turbulent flo w in the hot bubble. Although observationally hard to prove or disprov e, this turbulent structure is critically examined, It is found that, although the turbulence is not a numerical artefact, the full three-di mensional picture will most definitely differ from what is found in tw o dimensions. The implications for the interpretation of the models ar e discussed. Finally, the issue of the soft X-ray emission from PNe is considered, It is found that soft X-rays originate mainly from the th in interface between the hot bubble and the actual nebula.