SIMBAD references

The effects of dust extinction on the departure from axisymmetry in the morphology of planetary nebulae (PNs) are investigated through a comparison of the radio free-free emission and hydrogen recombination line images. The dust extinction maps from five compact PNs are derived using high-resolution (∼0".1) Hα and radio maps of the HST and VLA. These extinction maps are then analyzed by an ellipsoidal shell ionization model including the effects of dust extinction to infer the nebulae's intrinsic structure and orientation in the sky. This method provides a quantitative analysis of the morphological structure of PNs and represents a step beyond qualitative classification of morphological types of PNs.