Specke 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 15' and a separation of 60 milliarcseconds , in a 1002 wide band including H alpha . Among the possible explanations suggested for this remarkable source a r e (i) A relativistic jet breaking out from a weak spot in the supernova shell (ii) Relativistic ejection along 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. The secondary source has now d is appeared leaving us to decide between these two possibilities