What planetary nebulae can tell us about jets in core collapse   supernovae
  We compare the morphology of the core collapse supernova remnant (CCSNR) W49B with the morphology of many planetary nebulae (PNe), and deduce the orientation of the jets that shaped this CCSNR and estimate their energy. We find morphological features that are shared by some PNe and by the CCSNR W49B. In PNe these features, such as a barrel-shaped main body, are thought to be shaped by jets. We use these morphological similarities to deduce that the jets that shaped SNR W49B were launched along the symmetry axis of the `barrel', and to speculate that this CCSNR has two opposite lobes (or ears), that are too faint to be observed. We crudely estimate that the jets that shaped the CCSNR into a barrel shape had a kinetic energy that amounts to about one quarter to one third of the energy of the entire CCSNR. The morphological similarities strengthen the suggestion that jets play a central role in the explosion of massive stars. 
Ealeal Bear and Noam Soker
astro-ph.SR astro-ph.HE