SN 1987a (Type II Supernova)

Location:  Large Magellanic Cloud
Coordinates:  05 35 28.020 -69 16 11.07
Distance: 167,885 ly

Mainstream description
Remnant of a supernova whose radiation first reached Earth on February 23, 1987.  Its progenitor star was a blue supergiant cataloged as Sanduleak −69° 202.  At the time of the observed explosion blue supergiant stars were thought to be incapable of supernova activity.  Neutrinos from the explosion reached Earth hours before the visible light in quantities consistent with theoretical models for core-collapse supernova.  These same models predict that a neutron star should have formed in the center of the supernova remnant.  However, to this day no neutron star has been found, despite years of detailed observation.

Alternative description
The bright equatorial ring shows multiple Birkeland currents surrounding the remnants of the destroyed star which have formed a dual-lobed bipolar structure perpendicular to the axis of the ring.  The Birkeland currents are located in the outer sheath of an axial plasma current column while the supernova itself was the result of a stellar-scale z-pinch in the inner sheath, focused on the central star.  The z-pinch shares the same hourglass shape observed in many planetary nebulae, with the two fainter rings marking the opposing boundaries of the z-pinch.

SN 1987a (Type II Supernova)Shannon Sims