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A. P. S. Crotts (Columbia U.)
Supernova 1987A is the closest SN seen in nearly four centuries and a unique opportunity to study the mass loss nebula produced by a massive star at the end of its life. This nebula has been probed by a series of phenomena propagating through its interior, and its structure has been revealed in detail by its response. Its reaction to the ionizing UV pulse from the initial moments of the explosion has been used to determine density and composition as recombination lines evolve with a delay dependent on gas density and the nebula's geometry, and the three-dimensional geometry of the nebula has been mapped in detail by light echoes produced by the SN maximum-light flash. These reveal a nested hierarchy of structures, starting with a nearly empty region through which the SN eject is now expanding, surrounded by an hourglass-shaped nebula marked by the prominent three rings at its waste and crowns. The hourglass is itself embedded in a diffuse nebula which terminates in an apparent contact discontinuity some 4.5~pc in radius from the SN. This entire circumstellar envelope is contained in a lower density region excavated by the SN progenitor in its earlier phase. All of this information has been combined with kinematic information to tell us about timescales of the final mass loss phases of the star before exploded.
We will review the structure, density, composition and kinematics of this nebula, then show how it is further probed by its impact with the ejecta which is destroying it from within. We will present new and detailed images and spectroscopy of this phenomena which show some surprising results regarding how the nebula is evolving into a supernova remnant.
(This research has been supported by several grants from NASA, NSF and STScI.)
The author(s) of this abstract have provided an email address for comments about the abstract: arlin@astro.columbia.edu