Talk abstract details

Pre-Planetary Nebulae (PPNe) represent a relatively short, but all important, intermediate evolutionary phase in the evolution of AGB stars to Planetary Nebulae (PNe). Our unbiased, high-resolution imaging surveys with HST of young PNe and PPNe show very strong morphological similarities between these classes. Thus, our morphological scheme for PPN classification is easily extended to young PNe, preserving virtually all of the primary and secondary descriptors, and adding a few new secondary ones. The primary shaping of PNe likely begins before the PN phase. We have therefore been searching for clues to PNe formation and shaping mechanisms in PPNe.

Amongst the clues which we have uncovered in our multiwavelength (covering optical, mm-wave and radio wavelengths) studies of PPNe, we will discuss the following: (a) H$\alpha$ emission with P-Cygni profiles and very broad wings (b) massive collimated outflows (c) equatorial waists and disks with very large (millimeter-sized) dust grains.