February 10, 2009

Gamma-ray bursts erupt from neutron star

Astronomers using the U.S. space agency's Swift satellite and Fermi Gamma-ray Space Telescope report high-energy gamma-ray bursts from a neutron star.

National Aeronautics and Space Administration scientists said the object -- a rare type of neutron star known as a soft-gamma-ray repeater -- is emitting intense and frequent X-ray and gamma-ray flares.

At times, this remarkable object has erupted with more than a hundred flares in as little as 20 minutes, said Loredana Vetere, who is coordinating the Swift observations at Pennsylvania State University. The most intense flares emitted more total energy than the sun does in 20 years.

The object is in the southern constellation Norma. During the past two years, astronomers have identified pulsing radio and X-ray signals from it. Because of its recent outbursts, astronomers are classifying the object as a soft-gamma-ray repeater -- only the sixth such star that's been observed, NASA said.

In 2004, a giant flare from another soft-gamma-ray repeater was so intense it measurably affected Earth's upper atmosphere from 50,000 light-years away.

The ability of Fermi's gamma-ray burst monitor to resolve the fine structure within these events will help us better understand how magnetars unleash their energy, said Chryssa Kouveliotou, a NASA astrophysicist.