Article Posted on : - Mar 04, 2009

Illustration of the geriatric pulsar. NASA image

PARIS (BNS): Astronomers have studied images from NASA's Chandra X-ray Observatory and the European Southern Observatory's Very Large Telescope (VLT).

According to them the Chandra source is the ancient pulsar PSR J0108-1431 (J0108 for short), located only 770 light years from us. “The elongated object immediately to its upper right is a background galaxy that is unrelated to the pulsar. Since J0108 is located a long way from the plane of our galaxy, many distant galaxies are visible in the larger-scale optical image,” they said.

Researchers said that the position of the pulsar seen by Chandra from early 2007 is slightly different from the radio position observed in early 2001, implying that the pulsar is moving at a velocity of about 440,000 miles per hour. “The detection of this motion allowed an estimate of where J0108 should be located in the VLT image taken in 2000. The faint blue star just above the galaxy is a possible optical detection of the pulsar,” the researchers said.

Scientists are of the view that J0108 filled with radiation from particles spiraling around magnetic fields is shown along with heated areas around the neutron star's magnetic poles. “Both of these effects are expected to generate X-ray emission. Most of the surface of the neutron star is expected to be too cool to produce X-rays, but it should produce optical and ultraviolet radiation. Thus, multi-wavelength observations are important for providing a complete picture of these exotic objects,” they said.

They were of the opinion that at an age of about 200 million years, this pulsar is the oldest isolated pulsar ever detected in X-rays. Among isolated pulsars -- ones that have not been spun-up in a binary system -- it is over 10 times older than the previous record holder with X-ray detection. This pulsar is slowing down as it ages and converting some of the energy that is being lost into X-rays. The efficiency of this process for J0108 is found to be higher than for any other known pulsar, they added.