VLA-8.4-GHZ CONTINUUM OBSERVATIONS OF COMPACT PLANETARY-NEBULAE

We report 8.4 GHz radio continuum observations of 15 compact planetary nebulae. The high angular resolution (approximately 0.2 arcsec) image s obtained allow detailed examination of the structures of these nebul ae. A number of nebulae of very high surface brightness are found to h ave extreme bipolar structures. This suggests that such morphologies c an be developed in a very short time (< 10(3) yr). These bipolar nebul ae are likely to have descended from AGB stars with high-core masses ( > 0.6 M.)) which already possessed highly nonspherical envelopes at th e end of the AGB phase.