Magnetars are the only objects in space powered mainly by magnetism and are now considered to be the most likely explanation for soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). Their existence was first theorized in the late 1980s by the American astronomer Robert Duncan and the Canadian astronomer Christopher Thompson, who concluded that, in principal, neutron stars could be formed with magnetic fields that were very much stronger than those seen in familiar pulsars. Such an intense field, they reasoned, would put the star's surface under enormous stress, perhaps triggering starquakes and leading to intense bursts of high-energy radiation. In 1992, they used their magnetar theory to explain an enormously powerful gamma-ray burst detected on Mar. 5, 1979, and later identified with a young supernova remnant, N49, in the Large Magellanic Cloud and, later still, recognized as the first-recorded SGR. In 2002, Brian Kern and Chris Martin of the California Institute of Technology showed that the magnetar theory is the only reasonable explanation for the behavior of 4U0142+61, a faint object in Cassiopeia. In an ordinary pulsar, the optical pulsations are a diluted byproduct of the X-ray pulsars and are therefore relatively weaker. But in the case of 4U0142+61, a quarter of the pulsed output is visible light compared with only a 3% contribution from X-rays – exactly the behavior expected of a magnetar.
Related categories• TYPES OF STARS
Home • About • Copyright © The Worlds of David Darling • Encyclopedia of Alternative Energy • Contact