Posted: Tue, Mar 24, 2009, 6:31 AM ET (1031 GMT)
Astronomers using the Hubble Space Telescope have discovered a supermassive star that appears to have gone supernova earlier in its life than expected. The supernova, SN 2005gl, was spotted in Hubble archive images from 1997, sight years before it exploded. At the time the star was about 100 times the mass of the Sun and likely belonged to a class of supergiant stars called Luminous Blue Variables. According to models of such stars, this star should not have developed a iron core, the "ash" of fusion reactions, needed to trigger the supernova. Astronomers speculate that this star may have actually been a binary system that looked brighter and less evolved than it actually was, or that there may be other mechanisms for triggering supernova explosions.
