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Dead Star Has a Ring, But No Plans for a Wedding

NASA's Spitzer Space Telescope has found a bizarre ring of material around the magnetic remains of a star that essentially blew up. Also known as SGR 1900+14, this dead star belongs to a class of objects known as magnetars, which are cores of massive stars that blew up in supernova explosions. However, unlike other dead stars, they slowly pulsate with X-rays and have extremely strong magnetic fields. Scientists believe the ring was formed in 1998 when the magnetar erupted in a giant flare resulting in the crusty surface of the magnetar to crack. This resulted in sending out a flare, or blast of energy, that excavated a nearby cloud of dust, leaving an outer, dusty ring. This ring is oblong, with dimensions of about seven by three light-years, and appears to be flat, or two-dimensional. However, the scientists said they can't rule out the possibility of a three-dimensional shell.

Rings and spheres are common in the universe. Young, hot stars blow bubbles in space, carving out dust into spherical shapes. When stars die in supernova explosions, their remains are blasted into space, forming short-lived beautiful orbs called supernova remnants. Rings can also form around exploded stars whose expanding shells of debris ram into pre-existing dust rings, causing the dust to glow, as is the case with the supernova remnant called 1987A. But the ring around the magnetar SGR 1900+14 fits into none of these categories. For one thing, supernova remnants and the ring around 1987A cry out with X-rays and radio waves. The ring around SGR 1900+14 only glows at specific infrared wavelengths that Spitzer can see. "The universe is a big place and weird things can happen," said Stefanie Wachter of NASA's Spitzer Science Center at the California Institute of Technology, Pasadena, who found the ring serendipitously. "I was flipping through archived Spitzer data of the object, and that's when I noticed it was surrounded by a ring we'd never seen before." Wachter is lead author of a paper about the findings in this week's Nature—Huntsville, Alabama