Circumstellar infrared and scattered light echoes from SN 1987A

Abstract

The observed light curve and temperature evolution and the theoretically predicted initial UV burst of SN 1987A are used to construct models for the IR echo and scattered-light echo arising from circumstellar dust formed in the wind from the supernova progenitor's red supergiant phase. Observations of narrow UV emission lines suggest that some of this wind has been swept into a shell with a radius of order 10 to the 18th cm by the progenitor's blue supergiant wind. The UV observations also indicate a high abundance of oxygen with respect to carbon, which implies that the circumstellar dust should be composed primarily of silicate grains. Echo models are constructed by including the detailed emission and scattering properties of silicate grains and a spectrum of grain sizes. It is concluded that an IR echo has probably not been observed as of August, 1987. 46 refs.