SPACE.com -- Survey Links Nearby Pulsating Stars to Gamma Rays

Positions of all known pulsars in our Galaxy. Parkes multibeam survey pulsars and the young energetic radio pulsars are indicated. Positions are plotted in `Galactic coordinates' with the direction towards the Galactic Center at the center of the plot. Th

The new pulsar XTE J0052-727 was sufficiently bright in X-rays for its position to be localised to within about an arcminute by Rossi X-Ray Timing Explorer.

The X-ray Pulsar Signature: As a pulsar spins on its axis, beams of X-rays sweep out from its two magnetic poles, like the beam of a lighthouse. As the beams sweep past us, we see rapid brightenings in the X-ray flux one after another, producing a distinc

The 1.0 metre telescope of the South African Astronomical Observatory (SAAO) has been used to identify the optical counterparts to many X-ray pulsars.

Two X-Ray Pulsars Found in Nearby Galaxy

Cosmic X-rays Reveal Pulsar's Age

Pulsar Wobbles, Surprising Scientists

Pulsars May Be Older Than Scientists Thought


	Survey Links Nearby Pulsating Stars to Gamma Rays *By SPACE.com* Staff** posted: 09:00 am ET 12 April 2001

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Astronomers have found about 30 relatively young rotating stellar corpses, known as pulsars, in our Milky Way Galaxy, adding to a list of hundreds of similar but older objects. The energetic objects may be the sources of some of the mysterious gamma rays in our galaxy.

Pulsars were first discovered in 1967 as radio sources that blink on and off at a constant frequency. They are collapsed remains of exploded stars, known as neutron stars, which spin rapidly. This rotation causes the stars to lose energy, as jets of particles moving at the speed of light stream out their two magnetic poles.

These jets are now known to produce very powerful beams of light. The magnetic and rotational axes of a pulsar are misaligned, and so the beam of light sweeps around as the pulsar rotates, just like the spotlight in a lighthouse. As the beam sweeps over Earth, scientists see pulsars "turn on and off."

Young pulsars -- those that were recently formed after an ancient star exploded in an event known as a supernova -- rotate the fastest and have long been suspected of producing gamma rays, energetic cosmic emissions whose sources are not known for sure. Already, two of the most powerful gamma ray sources in the sky are thought to be pulsars, and two of the new pulsars appear to be linked to known regions where gamma rays emanate, researchers said.

The two newly found young pulsars are estimated at 13,000 and 34,000 years old.

While researchers have pinpointed some sources of gamma rays, many via the EGRET (Energetic Gamma Ray Experiment) instrument on the now deorbited Compton Gamma Ray Observatory satellite, only a handful have been identified. For example, seven gamma ray sources near the galactic plane have previously been identified as pulsars. But it's unclear what sorts of objects might be responsible for the rest.

"We've now found a further two pulsars that coincide with unidentified EGRET sources," said Nichi D'Amico of the Osservatorio Astronomico di Bologna, Italy. D'Amico, who presented the results at the Gamma Ray Astrophysics 2001 Symposium in Baltimore last week, noted that some uncertainty remained over the exact positions of the objects.

D'Amico worked with astronomers from the University of Manchester and other members of an international team using the Parkes 210-foot (64-meter) radio telescope in Australia. This survey has found more than 600 pulsars, nearly half the total cataloged to date.

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