- The Washington Times - Friday, November 8, 2002

A team of astrophysicists announced this week that it had confirmed the existence of a new type of star called a "magnetar," with the most powerful magnetic fields of any known object.
If the moon were a magnetar, lead researcher Alaa Ibrahim said, "it would suck every piece of metal from the Earth. It would be like living in an MRI." Mr. Ibrahim, a doctoral candidate at George Washington University, was the first to discover direct evidence of a magnetar's existence. The team has identified 10 of the stars.
The findings, the result of a year of work by Mr. Ibrahim and four other study co-authors, were published in two articles in the Astrophysical Journal Letters.
When a star 10 times the size of the sun runs out of fuel, it collapses inward in a supernova. Under the right conditions, Mr. Ibrahim said, violent supernovae can create magnetars.
This transformation can generate tremendous power. "The density of one of these is like crushing the mass of every ocean and every sea into a Coke can," Mr. Ibrahim said. The magnetic field generated is billions of times stronger than that of the sun.
Mr. Ibrahim made the discovery with a team of researchers from GW and NASA's Goddard Space Flight Center in Greenbelt. They were able to measure the magnetic field using NASA's Rossi X-Ray Timing Explorer satellite.
He studied a cosmic object known as SGR 1806-20, analyzing the flashes of gamma rays emitted by the star.
"These flashes are the distinguishing feature of magnetars," he said.
The bursts are caused by the star's magnetic field, which is so strong that it periodically cracks the star's iron crust in a "starquake." The resulting fireball causes a drop in the intensity of the radiation.
The unit of measure for magnetic field strength is the gauss, and the magnetar's is reportedly 1 million-billion gauss. The Earth's magnetic field, in comparison, is about a half-gauss.
The closest magnetar is 50,000 light-years from Earth, says the National Aeronautics and Space Administration. A light-year is the distance light travels in a year, about 5.88 trillion miles. Despite the distance, the magnetar's gamma-ray bursts affect the Earth's atmosphere, momentarily disrupting radio and communication signals.
Scientists have considered the existence magnetars since 1992, after observing a gamma-ray eruption from the gases surrounding a star. They speculated that the burst might have resulted from a strong magnetic field and estimated the strength of that field by gauging the speed of the star's rotation.
The observations lined up with theoretical projections made previously by other scientists. The new measurements indicate the magnetic field is 10 times stronger than originally believed.
"A long-standing debate over whether magnetars exist is, to a great extent, settled," Mr. Ibrahim said. "But it opens another avenue of testing: the laws of physics in this extreme magnetic field.
"One exotic effect of such a magnetic field is it can create [electron] particles out of nothing."



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