Scientists Catch Speeding Neutron Star with "Radar Gun" Technique, Confirm Theory

NASA scientists have observed a rare thermonuclear explosion on a neutron star that brightened it for so long that they could detect its motion as it moved towards and away from us on its orbit around a companion star. This enabled them to measure the star's orbital velocity using the Doppler effect in the same way a state trooper nabs speeding motorists.

This three-hour "superburst" also revealed the neutron star's spin frequency, confirming two key theories about neutron stars: that they can evolve into faster-spinning pulsars, and that the flickering of X rays frequently seen in short bursts, called burst oscillations, are a direct measurement of spin frequency.

Drs. Tod Strohmayer and Craig Markwardt of Goddard discussed the observation, made with NASA's Rossi X-ray Timing Explorer, at the joint meeting of the American Physical Society and the High Energy Astrophysics Division of the American Astronomical Society in Albuquerque, New Mexico.

"This burst allowed us to do some interstellar police work," said Markwardt of this neutron star, named 4U 1636-53. "Because the burst was so powerful -- a trillion times greater than the total U.S. energy consumption last year -- we could study the neutron star for much longer than usual. Its fast spin, well beyond the speed limit of most neutron stars, is strong evidence that these objects evolve into faster-spinning pulsars."

For more on the observation of the rare thermonuclear explosion, go to: http://www.gsfc.nasa.gov/news-release/releases/2002/02-056.htm