Mysterious Ring Structure Around Supernova 1987A

Mysterious Ring Structure Around Supernova 1987A
From the Hubble Space Telescope
NASA's Hubble Space Telescope's best images yet of a mysterious mirror-imaged pair of rings of glowing gas that are encircling the site of the stellar explosion supernova 1987A. One possibility is that the two rings might be "painted" by a high-energy beam of radiation or particles, like a spinning light-show laser beam tracing circles on a screen. The source of the radiation might be a previously unknown stellar remnant that is a binary companion to the star that exploded in 1987. Images taken by Hubble show a dim object in the position of the suspected source of the celestial light show.
The striking image shows three rings. The smaller "center" ring of the trio was seen previously. The larger pair of outer rings were also seen in ground-based images, but the interpretation was not possible until the higher resolution Hubble observations. Though all of the rings probably are inclined to our view (so that they appear to intersect), they probably are in three different planes. The small bright ring lies in a plane containing the supernova; the two rings lie in front and behind it.
To create the beams illuminating the outer rings, the remnant would need to be a compact object such as a black hole or neutron star with a nearby companion. Material falling from the companion onto the compact object would be heated and blasted back into space along two narrow jets, along with a beam of radiation. As the compact object spins it might wobble or precess about its axis, like a child's top winding down. The twin beam would then trace out great circles like jets of water from a spinning lawn sprinkler. If the rings are caused by a jet, however, the beams are extremely narrow (collimated to within one degree). The jet model explains why the rings appear to be mirror imaged, and why they appear to be symmetrical about a point offset from the center of the explosion.
The rings are probably on the surface of the hourglass shape. The hourglass was formed by a wind of slow-moving gas that was ejected by the star when it was a red supergiant, and a much faster wind of gas that followed during the subsequent blue supergiant stage. The hourglass was produced by the fact that the stellar wind from the red giant was denser in the equatorial plane of the star. When the star reached the blue supergiant stage, the faster winds tended to break out at the poles of the star. Energetic radiation from the supernova explosion illuminated the dense gaseous material in the equatorial "waist" of the hourglass, causing it to glow -- thus explaining the central bright ring. However, the two outer rings might be painted on the surface of the hourglass by a very different process, by the beams from the stellar remnant.
Image Title: Mysterious Ring Structure Around Supernova 1987A
based on press release for PHOTO NO.: STScI-PRC99-24

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Last Modified On: Sunday, December 17, 2000