Circumstellar interaction and a pulsar nebula in the supernova 1986j

Abstract

The supernova SN1986j was first discovered as a radio source in August 19861, although there were a number of pre-discovery observations. Here I show that the circumstellar interaction model for radio supernovae provides an adequate fit to the existing data, implies a time of explosion of about January 1983, and provides a guide for the future evolution of the radio source. A shell-like source structure is expected. The model together with very-long-baseline interferometry (VLBI) observations of the radio source, implies a shock velocity of ∼104 km s−1 and a pre-supernova mass loss rate of ∼10−4M⊙yr−1 for a wind velocity of l0 kms−1. A search for an infrared dust echo is warranted and an X-ray luminosity of ∼1040 erg s−1 is expected. The time behaviour of the optical flux and its high luminosity suggest that a central pulsar nebula is the energy source. The required properties are comparable to those expected in the early phases of the Crab nebula. The radiated energy from the pulsar nebula is absorbed by expanding, helium-rich material extending out to a velocity of ∼700 km s−1 or a radius of 8 x 1015 cm on September 1986. The radius of the pulsar nebula at that time is ∼5x1015 cm.