VLA 8.4 GHz continuum observations of compact planetary nebulae

We report 8.4 GHz continuum observations of 15 compact planetary nebulae. The high angular resolution (~0.2 arc sec) images obtained allow detailed examination of the structures of these nebulae. A number of nebulae of very high surface brightness are found to have extreme bipolar structures. This suggests that such morphologies can be developed in a very short time (<10 yr). These bipolar nebulae are likely to have decended from AGB stars with high core masses (>0.6 solar masses) which already possessed highly non-spherical envelopes at the end of the AGB phase.