CSI: Milky Way team works scene of dead star

Vikram Dwarkadas, Senior Research Associate in Astronomy & Astrophysics at the University of Chicago. Along with colleagues at NASA and elsewhere, Dwarkadas has been studying a strange ring circling a... Click here for more information.

Like a team of forensic detectives in a television show that could be called "CSI: Milky Way," a University of Chicago astrophysicist and his associates are piecing together how a mysterious infrared ring got left around a dead star that displays a magnetic field trillions of times more intense than Earth's.

NASA's Spitzer Space Telescope detected the ring around magnetar SGR 1900+14 at two narrow infrared frequencies in 2005 and 2007. The ringed magnetar is of a type called a soft gamma repeater (SGR) because it repeatedly emits bursts of gamma rays.

"The universe is a big place, and weird things can happen," said Stephanie Wachter of NASA's Spitzer Science Center at the California Institute of Technology. "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 enlisted Vikram Dwarkadas, a Senior Research Associate in Astronomy & Astrophysics at the University of Chicago, to help determine how the ring formed. Wachter, Dwarkadas and five other co-authors present the results of their investigation in the May 29 issue of the journal Nature.

This image shows a ghostly ring extending seven light-years across around the corpse of a massive star. The collapsed star, called a magnetar, is located at the exact center of... Click here for more information.

"It's the first time something like this has ever been seen around a magnetar," Dwarkadas said. Magnetars come from massive stars that have exploded as a core-collapse supernova. "These stars are at least eight times the mass of the sun, or more massive than that," he said.