Speckel Interferometry of SN 1987A and the "Mystery Spot"

Abstract

Two groups have independently studied SN1987A by the technique of optical speckle interferometry in the visible region of wavelengths about a month after the explosion. Both detect a secondary source a factor of ten fainter than the primary, at a position angle of 15o and a separation of 60 milliarcseconds, in a 100Å wide band including Hα. Among the possible explanations suggested for this remarkable source are (i) A relativistic jet breaking out from a weak spot in the supernova shell (ii) Relativistic ejection among the axis of rotation during the collapse (iii) Ionisation of a nearby gas cloud by a flash of hard radiation emitted at a very early stage, followed by recombination.