Morphologies of planetary nebulae ejected by close-binary nuclei

This paper examines the observed morphologies of planetary nebulae (PNs) that are known to have close-binary nuclei, in the light of theoretical studies of common-envelope ejection followed by wind shaping. Some of the physical aspects of the spiraling-in process and PN ejection are described, and the subsequent shaping of the PN via a stellar wind is examined. A list of the PNs known to have close-binary nuclei is presented together with the imagery of these PNs. The observed morphologies are discussed in the context of the theoretical predictions.