Scientists find oldest isolated pulsar ever

February 27th, 2009 - 2:51 pm ICT by ANI  

Washington, Feb 27 (ANI): With the help of NASAs Chandra X-ray Observatory, scientists have found the oldest isolated pulsar ever detected in X-rays.

The pulsar, PSR J0108-1431 (J0108 for short), which is about 200 million years old, turns out to be surprisingly active.

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 an X-ray detection.

At a distance of 770 light years, it is one of the nearest pulsars known.

Pulsars are born when stars that are much more massive than the Sun collapse in supernova explosions, leaving behind a small, incredibly weighty core, known as a neutron star.

At birth, these neutron stars, which contain the densest material known in the Universe, are spinning rapidly, up to a hundred revolutions per second.

As the rotating beams of their radiation are seen as pulses by distant observers, similar to a lighthouse beam, astronomers call them pulsars.

Astronomers observe a gradual slowing of the rotation of the pulsars as they radiate energy away.

Radio observations of J0108 show it to be one of the oldest and faintest pulsars known, spinning only slightly faster than one revolution per second.

The surprise came when a team of astronomers led by George Pavlov of Penn State University observed J0108 in X-rays with Chandra.

They found that it glows much brighter in X-rays than was expected for a pulsar of such advanced years.

Some of the energy that J0108 is losing as it spins more slowly is converted into X-ray radiation. The efficiency of this process for J0108 is found to be higher than for any other known pulsar.

This pulsar is pumping out high-energy radiation much more efficiently than its younger cousins, said Pavlov. So, although its clearly fading as it ages, it is still more than holding its own with the younger generations, he added.

At its advanced age, J0108 is close to the so-called pulsar death line, where its pulsed radiation is expected to switch off and it will become much harder, if not impossible, to observe.

We can now explore the properties of this pulsar in a regime where no other pulsar has been detected outside the radio range, said co-author Oleg Kargaltsev of the University of Florida.

To understand the properties of dying pulsars, it is important to study their radiation in X-rays. Our finding that a very old pulsar can be such an efficient X-ray emitter gives us hope to discover new nearby pulsars of this class via their X-ray emission, he added. (ANI)

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