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NASA's Swift, Fermi Probe Fireworks From a Flaring Gamma-Ray Star
February 11, 2009Astronomers using NASA's Swift satellite and Fermi Gamma-ray Space Telescope are seeing frequent blasts from a stellar remnant 30,000 light-years away. 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.
"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, 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 Oct. 3, 2008, 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. 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 Huntsville, Ala. The object has triggered the instrument more than 95 times since Jan. 22.
Using data from Swift's X-ray telescope, Jules Halpern at Columbia University captured the first "light echoes" ever seen from a soft-gamma-ray repeater. Images acquired when the latest flaring episode began show what appear to be expanding halos around the source. Multiple rings form as X-rays interact with dust clouds at different distances, with closer clouds producing larger rings. Both the rings and their apparent expansion are an illusion caused by the finite speed of light and the longer path the scattered light must travel.
"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 Greenbelt, Md., manages the Swift satellite. It is being operated in collaboration with partners in the U.S., the United Kingdom, Italy, Germany and Japan. NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics observatory developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.
To see the related images, visit:
http://www.nasa.gov/mission_pages/swift/bursts/gammaray_fireworks.html
For more information about the Swift satellite, visit:
http://www.nasa.gov/swift
For more information about the Fermi mission, visit:
http://www.nasa.gov/fermi
NASA
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 Huntsville, Ala. The object has triggered the instrument more than 95 times since Jan. 22.
Using data from Swift's X-ray telescope, Jules Halpern at Columbia University captured the first "light echoes" ever seen from a soft-gamma-ray repeater. Images acquired when the latest flaring episode began show what appear to be expanding halos around the source. Multiple rings form as X-rays interact with dust clouds at different distances, with closer clouds producing larger rings. Both the rings and their apparent expansion are an illusion caused by the finite speed of light and the longer path the scattered light must travel.
"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 Greenbelt, Md., manages the Swift satellite. It is being operated in collaboration with partners in the U.S., the United Kingdom, Italy, Germany and Japan. NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics observatory developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.
To see the related images, visit:
http://www.nasa.gov/mission_pages/swift/bursts/gammaray_fireworks.html
For more information about the Swift satellite, visit:
http://www.nasa.gov/swift
For more information about the Fermi mission, visit:
http://www.nasa.gov/fermi
NASA
Gamma-ray Current Events and Gamma-ray News RSSVERITAS telescopes help solve 100-year-old mystery: The origin of cosmic rays
Nearly 100 years ago, scientists detected the first signs of cosmic rays - subatomic particles (mostly protons) that zip through space at nearly the speed of light.
Iowa State researchers contribute to discovery of gamma rays from starburst galaxy
Iowa State University astrophysicists contributed to the recent discovery that a galaxy quickly creating new stars is also a source of high energy gamma rays.
Starburst galaxy sheds light on longstanding cosmic mystery
An international collaboration that includes scientists from the University of Delaware's Bartol Research Institute in the Department of Physics and Astronomy has discovered very-high-energy gamma rays in the Cigar Galaxy (M82), a bright galaxy filled with exploding stars 12 million light years from Earth.
NASA's Fermi Telescope Detects Gamma-Ray From
Nearby galaxies undergoing a furious pace of star formation also emit lots of gamma rays, say astronomers using NASA's Fermi Gamma-ray Space Telescope.
Gamma-ray photon race ends in dead heat; Einstein wins this round
Racing across the universe for the last 7.3 billion years, two gamma-ray photons arrived at NASA's orbiting Fermi Gamma-ray Space Telescope within nine-tenths of a second of one another.
Swift Makes Best-ever Ultraviolet Portrait of Andromeda Galaxy
In a break from its usual task of searching for distant cosmic explosions, NASA's Swift satellite has acquired the highest-resolution view of a neighboring spiral galaxy ever attained in the ultraviolet.
Fermi Large Area Telescope reveals pulsing gamma-ray sources
Scientists at the Naval Research Laboratory (NRL) Space Science Division and a team of international researchers have positively identified cosmic sources of gamma-ray emissions through the discovery of 16 pulsating neutron stars.
New experiment could reveal make-up of the universe
The detectors will become part of the Advanced Gamma Tracking Array (AGATA) experiment, currently based in Italy, which aims to create a 'fingerprint' of the inside of the atomic nucleus to understand the structure of all matter in the Universe, including human beings and the stars.
NRL's Large Area Telescope explores high-energy particles
NASA's Fermi Gamma-ray Space Telescope is making some exciting discoveries about cosmic rays and the Large Area Telescope aboard Fermi is the tool in this investigation.
NASA celebrates Chandra X-Ray Observatory's 10th anniversary
Ten years ago, on July 23, 1999, NASA's Chandra X-ray Observatory was launched aboard the space shuttle Columbia and deployed into orbit.
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