- (AP) - Astronomers believe they have
solved one of the universe's biggest mysteries and figured out the source
of at least some of the gamma ray bursts that bombard Earth's atmosphere
from time to time. These cosmic flashes may come from the explosion of
dying stars called supernovas.
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- Gamma ray bursts, high-energy flashes
of light that can be seen only from space, have befuddled scientists ever
since they were discovered just over 25 years ago. Such bursts occur, on
average, once a day in the observable universe.
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- A new window on the phenomenon opened
April 25, when a burst of gamma rays occurred at about the same time and
near the most unusual supernova ever observed.
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- In Thursday's issue of the journal Nature,
researchers at the California Institute of Technology in Pasadena said
the supernova may have generated the gamma ray burst by ejecting a stream
of material at close to the speed of light.
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- "I think we've found the missing
link between the two greatest explosions in the universe: a supernova and
a gamma ray burst," said Stan Woosley, chairman of astronomy and astrophysics
at the University of California at Santa Cruz. "It tells us the engine
that makes this supernova is also capable of making the gamma ray burst."
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- Since U.S. spy satellites first detected
gamma ray bursts, scientists have tried to explain them as products of
colliding neutron stars that coalesce into a black hole or as the result
of a massive black hole swallowing a neutron star.
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- A neutron star is the collapsed core
left after a star explodes. Neutron stars release energy by spewing light,
radio waves and particles.
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- The gamma ray findings are forcing scientists
to re-examine their ideas about supernovas, which are important because
they seed the galaxies with the iron, oxygen and carbon essential to life.
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- It's believed that most gamma ray bursts
occur billions of light-years away from Earth, but the April burst was
just 140 million light-years away, and was much weaker than the distant
ones. It was the first one ever observed in connection with a supernova.
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- Gamma ray bursts have higher energy than
all other forms of radiation, but that energy never affects Earth's surface
because it gets absorbed by the atmosphere. One such burst, detected on
Dec. 14, 1997, was the greatest cosmic blast since the Big Bang that created
the universe.
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