Pulsar

Pulsars are rotating neutron stars that are observable as sources of electromagnetic radiation. The radiation intensity varies at a regular period, believed to result from the rotation of the star.

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The pulsar was discovered in 1967, by Jocelyn Bell and Antony Hewish of the University of Cambridge, England. Initially baffled as to the unnaturally regular nature of its emissions, the pair dubbed their discovery LGM-1, for "little green men"; their pulsar was later dubbed CP 1919, and is now known as PSR 1919+21. Astrophysicist Peter A. Sturrock writes that "when the first regular radio signals from pulsars were discovered, the Cambridge scientists seriously considered that they might have come from an extraterrestrial civilization. They debated this possibility and decided that, if this proved to be correct, they could not make an announcement without checking with higher authorities. There was even some discussion about whether it might be in the best interests of mankind to destroy the evidence and forget it!" (Sturrock, 154)

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CP 1919 emits in radio wavelengths, but pulsars have subsequently been found to emit in the X-ray and gamma ray wavelengths. Hewish received the 1974 Nobel Prize in Physics for the work.

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Three distinct classes of pulsars are presently known to

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astronomers, according to the source of energy that powers the radiation:

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• Rotation-powered pulsars, where the loss of rotational energy of the star powers the radiation
• X-ray pulsars, where the gravitational potential energy of accreted matter is the energy source, and
• Magnetars, where the decay of an extremely strong magnetic field powers the radiation.

Although all three classes of objects are neutron stars, their observable behaviour and the underlying physics are quite different. There are, however, connections. For example, X-ray pulsars are probably old rotation-powered pulsars that have already lost most of their energy, and have only become visible again after their binary companions expanded and began transferring matter on to the neutron star. The process of accretion can in turn transfer enough angular momentum to the neutron star to "recycle" it as a rotation-powered millisecond pulsar.

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Pulsar: Significant pulsars ►



 

Neutron star: :This article is about the celestial body. "Neutron Star" was a 1966 Hugo award winning short story by Larry Niven...

Electromagnetic radiation: Electromagnetic radiation is a propagating wave in space with electric and magnetic components. These components oscillate at right angles to each other and to the direction of propagation....

Jocelyn Bell: REDIRECT Jocelyn_Bell_Burnell...