Published Paper Probes Pulsar Pair

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Jane Platt (818) 354-0880
Jet Propulsion Laboratory, Pasadena, Calif.

Jennifer Towell (514) 398-8585
McGill University, Montreal

News Release: 2004-114 April 28, 2004

Published Paper Probes Pulsar Pair

The only known gravitationally bound pair of pulsars -- extremely
dense, spinning stars that beam radio waves -- may be pirouetting
around each other in an intricate dance.

"Pulsars are intriguing and puzzling objects. They pack as much mass
as the Sun crammed into an object with a cross-sectional area about as
large as Boston," said Fredrick Jenet of NASA's Jet Propulsion
Laboratory, Pasadena, Calif. Jenet and Scott Ransom of McGill
University, Montreal, Quebec, Canada, have developed a theoretical
model to explain the behavior of this one-of-a-kind set of pulsars.

"The physics of radio pulsar emission has eluded researchers for more
than three decades," Jenet said. "This system may be the 'Rosetta
stone' of radio pulsars, and this model is one step toward its
translation."

The research appears in the April 29 issue of the journal Nature.
Jenet and Ransom studied the recently-discovered double pulsar system,
in which two spinning pulsars orbit each other.

The discovery of the two-star system, officially named PSR
J0737-3039B, was announced in 2003 by a multinational team of
researchers from Italy, Australia, the United Kingdom and the United
States. Those researchers proposed that the duo contained one spinning
pulsar and a neutron star. Later in 2003, scientists working at the
Parkes Observatory in New South Wales, Australia, determined that both
stars are actually pulsars. This discovery marked the first known
example of a "binary," or double, pulsar system. The stars are
referred to as A and B.

Pulsars emit high-intensity radio radiation into a narrow beam. As the
pulsar rotates, this beam moves in and out of our line of sight.
Hence, we see periodic bursts of radio radiation. In this sense, a
pulsar works like a lighthouse, in which the light may be on all the
time, but it appears to blink on and off. Scientists were surprised to
find that the B pulsar is on only at certain locations in its orbit.
"It's as though something is turning B on and off," Jenet said.

According to Jenet and Ransom, this "something" is closely related to
the radio emission beam emanating from the A pulsar. They believe that
B becomes bright when it is illuminated by emission from A. Jenet and
Ransom used Einstein's Theory of General Relativity to predict the
future evolution of this pulsar system. The theory implies that
gravitational effects will change the emission pattern of A, which
will then alter the exact orbital locations where B becomes bright.

The double pulsar system is located about 2,000 light years, or 10
million billion miles, from Earth. Jenet and Ransom based their
research on observations made at the Green Bank Telescope in West
Virginia.

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