The Structure of the Circumstellar Envelope of SN 1987A

Abstract

The volume around the SN 1987A contains a variety of structures, not just the three rings glowing in recombination lines. Many of these are revealed by light echoes, so are mapped in three dimensions by our optical imaging of the SN environs. The rings reside in a bipolar nebula containing them at its waist and crowns, and which is itself contained in a larger, diffuse nebula with a detectable equatorial overdensity. This diffuse nebula terminates in a denser wall which likely marks the inner edge of a bubble blown by the progenitor's main sequence wind. Along with mapping these structures, we measure spectroscopically the velocity of the gas, revealing, for instance, kinematic ages for the inner and outer rings in close agreement with each other. The presence of these structures, their ages and morphologies must be included in models explaining the evolution of the progenitor star and its mass loss envelope.