Axisymmetrical structures of planetary nebulae and SN 1987A

Abstract

In this paper I review some recent models and ideas for the formation of axisymmetrical structures of planetary nebulae and the three rings of SN 1987A, as follows. (a) I review the general role of binary companions, including brown dwarfs and planets. (b) I propose a mechanism for axisymmetrical mass loss on the AGB that may account for the axially symmetric structures of elliptical planetary nebulae and that operates for slowly rotating AGB stars, 10 −4Ω Kep ≲Ω≲10 −2Ω Kep , where Ω Kep is the equatorial Keplerian angular velocity. (c) I propose a model for the formation of the two outer rings of SN 1987A, which is based on the numerical simulation of Soker (1989), and discuss a mechanism for their displacement from the exploding star.