[Previous] | [Session 6] | [Next]
S. Kwok (University of Calgary), K.Y.L. Su (Valparaiso University), R. Sahai (JPL)
Although the interacting stellar winds process has long been thought to be responsible for the shaping of planetary nebulae, it is now realized the shaping process occurs early, probably within a few hundred years from the end of the asymptotic giant branch evolution. The observations of young planetary nebulae are therefore essential and should give important constraints to the theories of dynamical shaping. In this paper, we report the HST WFPC2 imaging of a number of young planetary nebulae, finding evidence for collimated ouflows, point-symmetric structures and multi-polar lobes. The origin of these structures is discussed in the context of dynamical evolution of planetary nebulae.