Date: 23 Feb 2007
Satellite: Hubble Space Telescope
Depicts: Inner Ring, SN1987A
Copyright: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)

This series of Hubble images of supernova 1987A's remnant, shows the evolution of the inner ring of gas around the remains of the exploded star at the centre.

The stellar blast was first spotted 20 years ago. The explosion is one of the brightest supernova blasts in more than 400 years. Hubble began watching the blast's aftermath shortly after it was launched in 1990.

The growing number of bright spots on the ring was produced by an onslaught of material unleashed by the blast. The shock wave of material is slamming into the ring's innermost regions, heating them up, and causing them to glow. The ring, about a light-year across, was probably shed by the star about 20 000 years before the star exploded.

Astronomers detected the first bright spot in 1997, but now there are dozens of spots around the ring. Only Hubble can resolve the individual bright spots. In the next few years, the entire ring will be ablaze as it absorbs the full force of the crash. The glowing ring is expected to become bright enough to illuminate the star's surroundings, providing astronomers with new information on how the star expelled material before the explosion.

The bright spot that appears to be on the ring at lower right is actually a foreground star. Supernova 1987A is 163 000 light-years away in the Large Magellanic Cloud.

The images were taken between 1994 and 2006 with Hubble's Wide Field Planetary Camera 2 and Advanced Camera for Surveys. From top to bottom, left to right, the observation dates are:

• 24 September 1994
• 06 February 1998
• 23 March 2001
• 05 January 2003
• 15 December 2004
• 06 December 2006