Spectrophotometry of SN 1987A from the Kuiper Airborne Observatory

Abstract

Explosion calculations of SN 1987A generate pictures of Rayleigh-Taylor fingers of radioactive 56Ni (56Ni → 56Co → 56Fe) which are boosted to velocities of several thousand km s-1. From the KAO observations of the mid-IR iron lines, a picture of the iron in the ejecta emerges which is consistent with the ‘frothy iron fingers’ having expanded to fill about 50% of the metal-rich volume of the ejecta (vm ≤ 2500 km s-1). The ratio of the nickel line intensities I([Ni I]7.5µm)/I([Ni II]6.6µm) yields a high ionization fraction of xNi ≥ 0.9 in the volume associated with the iron-group elements at day 415, before dust condenses in the ejecta.