Credit: ESA/INTEGRAL/IBIS-SIGRI (Rea et al. 2009)
A Magnetic, High Energy Personality
The strongest magnets in the Universe are a group of dead stars called, appropriately enough, magnetars. Magnetars possess magnetic fields which are 1015 times stronger than the earth's magnetic field (that's a million billion times), so extreme that they could slow a bullet train on earth from the distance of the moon. Very few magnetars have been identified, and they're only a few miles across, so they're impossible to see at cosmic distances. But they can (and do) make their presence known quite vociferously by undergoing strong outbursts (possibly produced by the fracturing of the star's iron crust by the superstrong magnetic field). These outbursts can be so strong that, from clear across the Galaxy, they can damage satellites orbiting earth. For this reason and because magnetars provide a natural laboratory for the study of material in superstrong magnetic fields, astronomers are extremely interested in these objects. The latest magnetar found, called SGR 0501+4516, was identified about a year ago from an outburst observed by the Swift Gamma-ray burst explorer, the XMM-Newton X-ray Observatory, and INTEGRAL. The acronym SGR stands for "soft gamma-ray repeater" since magnetars emit low energy gamma rays during their outbursts, and unlike other Gamma-ray bursters, they are not destroyed by the outburst. The INTEGRAL observation is shown above - a detection of a strong point source of hard X-ray emission on the left, which then, about ten days later, faded away (right). The inset shows an artist's interpretation of the surface of a magnetar and the strong magnetic field lines which emanate from it, along with a series of spiky outbursts observed by XMM-Newton. This INTEGRAL observation is the first detection of transient hard X-ray emission from a magnetar.
Published: October 26, 2009
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Page Author: Dr. Michael F. Corcoran
Last modified Sunday, 01-Nov-2009 12:10:38 EST