found: Work cat.: 2001038362: Post-AGB objects as a phase of stellar evolution, 2001:CIP pref. (the term proto-planetary nebulae (PPNe; also called post-asymptotic giant branch, or shortly, post-AGB objects) created to express the belief that in the near future these objects will become planetary nebulae)
found: Dict. astron.(protoplanetary nebula: an early stage in the formation of a planetary nebula in which the central star has shed its outer layers exposing the hot stellar core from which ultraviolet light begins to ionize the surrounding cloud of gas and dust, and for a brief phase the circumstellar envelope contains both hot ionized material near the star and cool molecular material far from the star)
notfound: Gloss. astron. astrophys.;McGraw-Hill dict. sci. tech.