Astronomers discover 'monstrous' supernova

NASA has discovered the brightest and most violent explosion of a star ever recorded, it said Monday, an event over 240 million light years away that could provide a preview of similar fireworks in our own galaxy.

The stellar explosion blew up a star more than 150 times larger than our own sun, according to observations from ground telescopes and NASA's Chandra X-ray Observatory.

"This was a truly monstrous explosion, a hundred times more energetic than a typical supernova," said Nathan Smith of the University of California at Berkeley, who led a team of astronomers from California and the University of Texas in Austin.

"We've never seen that before," he said.

The Chandra-observed supernova, called SN 2006gy, is the most intrinsically bright stellar explosion ever recorded. Other supernovas have appeared brighter to our eyes, but that was because those explosions occurred closer to Earth.

NASA scientists said the star that produced the supernova apparently expelled much of its mass prior to exploding, a process similar to one scientists have been observing in Eta Carinae, a massive star a mere 7,500 light years away in our own Milky Way galaxy.

Mario Livio of the Space Telescope Science Institute in Baltimore, who was not involved in the research, told NASA that astronomers should keep an eye on the star's progress.

"Eta Carinae's explosion could be the best star-show in the history of modern civilization," he said.

Massive stars go supernova at the end of their lifecycle, after they have exhausted the fuel needed to sustain the nuclear reactions in their cores. When this happens, a star collapses under its own gravity and releases a huge amount of energy.

What remains is usually a black hole or a neutron star, but NASA scientists speculate SN 2006gy could have exploded in a different way, with its collapse leading to runaway thermonuclear reactions that blew its mass and energy into the far reaches of space.

Such a reaction would go against traditional theories about the birth and death of stars in the early universe, said Smith.

"In terms of the effect on the early universe, there's a huge difference between these two possibilities," said Smith. "One pollutes the galaxy with large quantities of newly made elements and the other locks them up forever in a black hole."