University of California-Berkeley astronomers said the supernova might be the first example of a type of massive exploding star rare today, but probably common during the very early universe.
Unlike typical supernovas that reach a peak brightness in days to a few weeks, SN2006gy took 70 days to reach full brightness and today, nearly eight months later, it still is as bright as a typical supernova at its peak.
UC-Berkeley post-doctoral fellows Nathan Smith and David Pooley estimate the star's mass at between 100 and 200 times that of the sun.
"This was a truly monstrous explosion, a hundred times more energetic than a typical supernova," said Smith, who led a team of astronomers from UC-Berkeley and the University of Texas. "That means the star that exploded might have been as massive as a star can get -- about 150 times that of our sun. We've never seen that before."
The research is to be published in The Astrophysical Journal.