NASA’s Swift, Fermi Probe Fireworks From a Flaring Gamma-Ray Star
“At times, this remarkable object has erupted with more than a hundred flares in as little as 20 minutes,” 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
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. Although only about 12 miles across, a neutron star contains more mass than the sun. 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. 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. Astronomers think magnetars power their flares by tapping into the tremendous energy of their magnetic fields.
“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
Using data from Swift’s X-ray telescope,
“X-rays from the brightest bursts scatter off of dust clouds between us and the star,” Halpern said. “As a result, we don’t really know the distance to this object as well as we would like. These images will help us make a more precise measurement and also determine the distance to the dust clouds.”
NASA’s Wind satellite, the joint NASA-Japan Suzaku mission, and the European Space Agency’s INTEGRAL satellite also have detected flares from SGR J1550-5418.
NASA’s Goddard Space Flight Center in
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