These is a collection of nine fait, nearby planetary nebulae of large angular
extent, made in OIII and Halpha with the 30cm Skinakas Scmidt camera.
This study suggested that the mechanism primarily influencing the
shaping of aging PNe is the interaction at an early or advanced stage between the nebular material
and the ambient interstellar medium (ISM). Clear evidence for such a process is shown,
increasing substantially the number of cases where a PN-ISM interaction has been identified.
Xilouris, K. M.; Papamastorakis, J.; Paleologou, E.; Terzian, Y 1996A&A...310..603X
This is a study of the halo around NGC 6853 which for the first time
reveals details of interaction with the ISM.
Papamastorakis, J.; Xilouris, K. M.; Paleologou, E. 1993A&A...279..536
(kx8u@virginia.edu)