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Giant Blast

July 3, 2013

A run-of-the-mill gamma-ray burst is one of the most powerful outbursts in the universe. It lasts only a minute or so, but in that time it beams as much energy into space as the Sun will produce in its entire lifetime.

But a recently discovered type of gamma-ray burst puts an ordinary one to shame. It blazes for hours before the gamma rays fade away.

Both types of outbursts appear to be powered by the explosions of massive stars. When such a star uses up the nuclear fuel in its core, the core collapses to form a black hole. The hot gas in layers around the core falls inward, creating a shockwave that blasts outward, ripping the star apart as a supernova. As part of the process, beams of gamma rays — the most powerful form of energy — blast out through the star’s poles. If Earth happens to lie in the path of such a beam, we see it as a gamma-ray burst.

Most of these stars are fairly small. But two teams of astronomers say the newly found bursts are produced by stars that are hundreds or even thousands of times wider than the Sun.

It takes a long time for such a huge star’s outer layers to collapse and then rebound as a supernova. The lengthy collapse feeds the gamma-ray burst for up to several hours. The burst ends when the shockwave rips the star apart. Although the gamma-ray burst comes to an end, the fireworks are just getting started: The supernova will shine as brightly as an entire galaxy of normal stars — an outburst that lasts for months.


Script by Damond Benningfield, Copyright 2013

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