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Evolution from the Asymptotic Giant Branch to Planetary Nebulae

The post‐asymptotic‐giant‐branch (post‐AGB) or pre‐planetary nebulae (PPN) phase of stellar evolution plays an important role in the dynamical shaping of PNe. While the interacting stellar winds model has achieved tremendous success in the explaining of the 1‐D structures (shells, crowns, haloes) of PNe, the origins of arcs, rings, and multipolar structures remain a mystery. The synthesis of gas‐phase molecules and solid‐state compounds that begin in the stellar winds from AGB stars also undergo significant evolution during the post‐AGB phase. Organic compounds of both aliphatic and aromatic structures are produced, which carries significant implications on the chemical enrichment of the interstellar medium.