The term proto-planetary nebulae (PPNe) in the context of the late stages of stellar evolution was created only slightly more than 20 years ago to express the belief that in the near future these objects will become planetary nebulae (PNe). The first proto-planetary nebulae (called also post-Asymptotic Giant Branch, or shortly post-AGB objects) AFGL 2688 and AFGL 618 were discovered in mid- seventies in course of the Air Force Sky Survey. Investigation...
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