News Releases
7/3/08: Unique Stellar System Gives Einstein a Thumbs-Up.
6/23/08: Radio Telescopes Reveal Unseen Galactic Cannibalism.
6/2/08: Mining for Molecules in the Milky Way.
5/22/08: Radio Telescopes to Keep Sharp Eye on Mars Lander.
5/21/08: Luck Reveals Stellar Explosion's First Moments.
5/20/08: Phoenix Mars Lander Mission.
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Artist's Conception of Double Pulsar System PSR J0737-3039A/B (Credit: Daniel Cantin, DarwinDimensions, McGill University).
Unique Stellar System Gives Einstein a Thumbs-Up
Taking advantage of a unique cosmic coincidence, astronomers have measured an effect predicted by Albert Einstein's theory of General Relativity in the extremely strong gravity of a pair of superdense neutron stars. The new data indicate that the famed physicist's 93-year-old theory has passed yet another test.
The scientists used the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) to make a four-year study of a double-star system unlike any other known in the Universe. The system is a pair of neutron stars, both of which are seen as pulsars that emit lighthouse-like beams of radio waves.
"Of about 1700 known pulsars, this is the only case where two pulsars are in orbit around each other," said Rene Breton, a graduate student at McGill University in Montreal, Canada. In addition, the stars' orbital plane is aligned nearly perfectly with their line of sight to the Earth, so that one passes behind a doughnut-shaped region of ionized gas surrounding the other, eclipsing the signal from the pulsar in back.
"Those eclipses are the key to making a measurement that could never be done before," Breton said.
Einstein's 1915 theory predicted that, in a close system of two very massive objects, such as neutron stars, one object's gravitational tug, along with an effect of its spinning around its axis, should cause the spin axis of the other to wobble, or precess. Studies of other pulsars in binary systems had indicated that such wobbling occurred, but could not produce precise measurements of the amount of wobbling.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.