1996A&A...311..997G

A quantitative analysis of the origin and formation of double-envelope planetary nebulae is elaborated based on the concept of dynamic separation of a gaseous envelope into two parts under the action of light pressure due to L_α-radiation. In combination with Paczynski's evolution model for central stars of planetary nebulae, this concept brings about the formation of three-envelope planetary nebulae in the definitive stage of evolution of their central stars. The calculated magnitudes of the most important parameters of double-envelope nebulae, the ratios of the sizes d₂/d₁ and masses M₂/M₁ of both envelopes are in accordance with observations. The double-envelope stage is an evolution phase in the life of the nebula and its nucleus through which all planetary nebulae should pass without exception. A number of arguments are advanced against the concept of the origin of double- and three-envelope nebulae as a result of multiple outbursts of gaseous matter from the central stars. The possibilities of interacting wind in the origin of two- or three-envelope nebulae is discussed also.