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Pigwidgeon Took · 06-22-2009, 07:02 PM

Quote:

Originally Posted by Mistress Vondella

"Thank you for joining us, ladies. Satine, consider my not taking house points off you thanks for bringing the extra supplies for the Hufflepuffs. Rachel, 5 points for arriving late."

He looked around the room again and continued:

Certain star explosions, called hypernovae, have much greater reach. Ten times more powerful than typical supernovae, hypernovae are the source for long-duration gamma ray bursts (GRBs), which are high-energy beams emitted along the dying star's axis. A GRB could travel 6,500 light-years and still inflict terrific damage on Earth, Thomas says.

The number of GRBs is much less than the number of supernovae, but the exact rate in our galaxy is still a matter of debate. A few years ago, a group of astronomers calculated that the likelihood of a GRB going off near us was very low, due to the fact that GRBs tend to arise in young galaxies with less heavy elements than the Milky Way.

But Thomas says that subsequent analyses have called this calculation into question, partly because our galaxy has merged in the past with smaller, younger galaxies that could have brought GRB-ticking-time-bombs in with them. "Our likelihood for hosting a GRB could vary with time," Thomas says.

He speculates that on average a GRB lights up our galaxy about once every 10 million years.

Jude raised his hand, "Excoos meh, Professoah, bu' who is dis 'Thomas' man yer talkin' 'bou'?" he asked, his pen poised over his parchment, waiting to finish his sentence.

06-22-2009, 07:02 PM	#24 (permalink)
Pigwidgeon Took Swedish Short-Snout Join Date: Dec 2005 Location: Wangdoodleland. Posts: 31,294	Russian Dancing Snake-Twin \| Jam Pony Rider \| Has Snuffed It! Quote: Originally Posted by Mistress Vondella "Thank you for joining us, ladies. Satine, consider my not taking house points off you thanks for bringing the extra supplies for the Hufflepuffs. Rachel, 5 points for arriving late." He looked around the room again and continued: Certain star explosions, called hypernovae, have much greater reach. Ten times more powerful than typical supernovae, hypernovae are the source for long-duration gamma ray bursts (GRBs), which are high-energy beams emitted along the dying star's axis. A GRB could travel 6,500 light-years and still inflict terrific damage on Earth, Thomas says. The number of GRBs is much less than the number of supernovae, but the exact rate in our galaxy is still a matter of debate. A few years ago, a group of astronomers calculated that the likelihood of a GRB going off near us was very low, due to the fact that GRBs tend to arise in young galaxies with less heavy elements than the Milky Way. But Thomas says that subsequent analyses have called this calculation into question, partly because our galaxy has merged in the past with smaller, younger galaxies that could have brought GRB-ticking-time-bombs in with them. "Our likelihood for hosting a GRB could vary with time," Thomas says. He speculates that on average a GRB lights up our galaxy about once every 10 million years. Jude raised his hand, "Excoos meh, Professoah, bu' who is dis 'Thomas' man yer talkin' 'bou'?" he asked, his pen poised over his parchment, waiting to finish his sentence. __________________ •Looking for some color?• (click the button... you know you want to)