NASA’s Swift satellite witnesses frequent blasts

New York (PTI): Astronomers using NASA’s Swift satellite and Fermi Gamma-ray Space Telescope have been witnessing frequent blasts from a stellar remnant 30,000 light-years away, the American space agency reported.

The high-energy fireworks arise from a rare type of neutron star known as a soft-gamma-ray repeater. Such objects unpredictably send out a series of X-ray and gamma-ray flares, NASA reported.

“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,” Vetere said.

The object, which has long been known as an X-ray source, lies in the southern constellation Norma. During the past two years, astronomers have identified pulsing radio and X-ray signals from it.

The object began a series of modest eruptions on October 3, 2008 and then settled down. It roared back to life Jan 22 with an intense episode. Because of the recent outbursts, astronomers will classify the object as a soft-gamma-ray repeater – only the sixth known.

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.

Scientists think the source is a spinning neutron star, which is the superdense, city-sized remains of an exploded star. The object has been cataloged as SGR J1550-5418.

While neutron stars typically possess intense magnetic fields, a subgroup displays fields 1,000 times stronger, NASA said. These so-called magnetars have the strongest magnetic fields of any known object in the universe.

SGR J1550-5418, which rotates once every 2.07 seconds, holds the record for the fastest-spinning magnetar.

“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, an astrophysicist at NASA’s Marshall Space Flight Center in Huntsville, U.S..