Subsequent to the discovery of the bright elliptical ring around Supernova 1987A, which is shown in the preceding two pictures, astronomers found two much larger and dimmer nebulous structures located to either side of the supernova remnant. Their nature was in doubt until this remarkable image was obtained with the HST in February 1994. The image, taken in the red light of the hydrogen atom, shows that the two dimmer structures are also rings. Furthermore, it seems that the two outer rings are hoop-shaped but are so narrow that even the HST cannot determine how wide any given part of the hoop is.
The nature of the two outer rings near Supernova 1987A is the subject of much conjecture. Are they real nebulosities or are they emission patterns, 'painted' on a dark canvas by beams of energetic particles or radiation from a strategically located object? Or yet something else? It is fair to say that they have not been explained to the general satisfaction of astronomers. This is not very surprising, as no similar phenomenon has ever been seen in space.
Credit: C. Burrows (STScl and ESA), and NASA