THE INFLUENCE OF STELLAR EVOLUTION ON PLANETARY-NEBULA FORMATION

A discussion of how the fact that the central star evolves while the p lanetary nebula is forming affects the formation of the nebula. Numeri cal models point to a number of effects, such as more efficient shapin g in the early phases and the formation of a surrounding shell. It is also found that for identical initial density distributions, quickly e volving (more massive) stars will form bipolar PNs and more slowly evo lving stars will form elliptical PNs.