Tuesday, Nov 5, 2002 2:31 PM
Keep your credit cards and computer disks away from this one. It's a magnet so powerful, it could suck the coins out of your pockets from as far away as the Moon.
Fortunately, this magnet is much further away -- as much as 40,000 light years distant from Earth. It's actually a star named SGR 1806-20, one of only four such stars known as magnetars, and billions of times more magnetic than the most powerful magnets built on Earth.
In 1979, scientists observed a huge energy outburst in space which, marked the discovery of a new class of stars now known as Soft Gamma-ray Repeaters (SGR). Scientists theorized that these objects must be highly magnetic in order to burst with such magnitude, and called them magnetars.
"Scientists have been puzzled for a decade about the nature of these mysterious stars," says Dr. Samar Safi-Harb, the principal investigator on the research project. "For many years, a great deal of evidence suggested that these stars were magnetars, but we didn't have a direct measurement of their magnetic fields."
Safi-Harb explains that when the researchers finally were able to study these stars directly, the features seen in the X-ray spectrum unveiled a magnetic field a thousand trillion times greater than the Sun's magnetic field, settling a long-standing debate.
SGR 1806-20 is a neutron star, what's left of a collapsed star once about ten times more massive than the Sun. These neutron stars are born in supernova explosion, one of the most fascinating events in the universe, that witnesses both the death of a massive star and the birth of a compact star formed under such pressure that it is composed entirely of neutrons - raw building blocks of matter.
"This neutron star could be as small as Winnipeg, but with a temperature several million times warmer," Safi-Harb notes.
The team of researchers which confirmed the existence of the magnetar also included: Dr. Alaa Ibrahim, a doctoral candidate at George Washington University conducting research at NASA Goddard Space Flight Center in Greenbelt, Maryland.; Dr. Jean Swank of NASA Goddard (Rossi Explorer Project Scientist); Dr. Silvia Zane of the Mullard Space Science Laboratory in the United Kingdom; Roberto Turolla of the University of Podova, Italy; and Dr. William Parke of the George Washington University in Washington.
Ibrahim made the discovery with Safi-Harb when he was a visiting scientist at the U of M doing research with her on a project funded by the Natural Sciences and Engineering Research Council of Canada and a University of Manitoba Research Grant. The data was acquired using NASA's Rossi X-Ray Timing Explorer (RXTE) satellite.
"If the Moon were this magnetic, it would rearrange the molecules in our body," says Ibrahim. "Although one would not want to get close to such an object, we now have a method of probing from afar to learn about the physics of matter under extreme gravitational and magnetic forces."
The discovery was also announced today by NASA and George Washington University following the publication of the discovery in Astrophysical Journal.
An animation showing the motion of particles inside a magnetar can be found at:
For more information, contact:
Dr. Samar Safi-Harb
Department of physics and astronomy
University of Manitoba
Ph: (204) 474-7104 or (204) 475-7890
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