Are there detectable infrared arcs around supernova 1987A?

Abstract

The possibility is examined that the recently discovered arcs of reflected light in the LMC around SN 1987A may be accompanied by detectable arcs of thermal IR emission from dust heated by the UV-visual output of the supernova. Detectability depends on the ratio Zeta = Q(a)/Q(p)P, where Q(a) and Q(s) are the visual absorption and scattering efficiencies of the dust and P is the small-angle scattering phase function. Calculations for spherical grains of graphite and silicate are presented. A Mathis-Rumpl-Nordsieck distribution of grain sizes has an effective Zeta of roughly 0.1. Some grain size distributions more heavily weighted toward small grains in the Galaxy have values of Zeta roughly one to two. With current instrumentation, the flux is below or at best close to the detection limit.