binary pulsar


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binary pulsar

A pulsar that is in orbit about another star, and is detected by its intrinsic emission of radiation (usually radio waves) rather than by radiation resulting from mass transfer (see X-ray pulsators). The orbital motion is inferred from apparent changes in the pulse period as the pulsar orbits its companion; the companion star, which is not generally detected directly, can be a neutron star, a white dwarf, a low-mass star, or even a supergiant. Systematic surveys have discovered large numbers of binary pulsars, in particular binary millisecond pulsars, in globular clusters, but they also occur in the galactic disk. The properties of the systems vary widely: the pulse period ranges from 0.0016 second (for PSR 1957+20) to about one second; the orbital periods range from several hours to several years.

PSR 1913+16 was the first binary pulsar to be discovered (in 1974), and is still sometimes called ‘the binary pulsar’. It has a pulse period of 59 milliseconds. Its short period and highly eccentric (e = 0.617) orbit have led to accurate determinations of the system's parameters. The masses of the pulsar and the unseen companion are identical, and at 1.4 solar masses are equal to the Chandrasekhar limit for collapse to a neutron star. The orbital period is decreasing at a rate of 75 microseconds per year, implying that the stars are spiraling together. The only mechanism for losing orbital energy in this system is gravitational waves, and the analysis of PSR 1913+16 gives a rate of energy loss that is precisely in accord with the theory of general relativity. The pulsars PSR 2127+11C in the globular cluster M15 and PSR 1534+12 in the galactic disk are the two other examples of systems like PSR 1913+16 presently known. See also black-widow pulsars; planet pulsar.

binary pulsar

[′bīn·ə·rē ′pəl‚sär]
(astronomy)
A pulsar which forms one component of a binary star.
References in periodicals archive ?
He suggests that during certain encounters between a binary pulsar (a neutron star paired with a white dwarf) and an ordinary star that has a planet orbiting it, the ordinary star and the white dwarf would trade places.
The research, which led to the discovery of the binary pulsar, was completed at one of the world's most advanced radio astronomy observatories at the time, located in Arecibo, Puerto Rico.
Combined with the new mass estimate, this suggests that Cygnus X-3 is the first known star system likely to form a binary pulsar, Charles says.
University report that they have found the companion of the binary pulsar PSR1855+09, one of the "millisecond pulsars" with a pulse period of 5.
Astrophysicists have discovered the swiftest binary pulsar yet recorded, with a pulse period of 5.
The first binary pulsar was discovered in 1974, and we now know the two bodies are getting slowly closer at just the rate expected if they are losing energy by radiating gravitational waves.
86 millisecond binary pulsar that was discovered in the Parkes Multibeam (PM) survey.
Prof Lyne then considered the creation of binary pulsar systems and millisecond pulsars, objects rotating so rapidly that the pulse of radiation from the star occurs hundreds of times a second.
The subsequent development of instrumentation within the labs contributed to the discovery of the binary pulsar system by Joe Taylor and Russel Hulse for which the two men received the 1993 Nobel Prize in physics.
In 1993, he shared the Nobel Prize in Physics for the discovery of the first binary pulsar, which enabled testing of Einstein's General Theory of Relativity and resulted in the first observational evidence for the existence of gravitational radiation.
So if we examine a binary pulsar (a pulsar in a mutual orbit with an ordinary star) we can use the pulsar as a clock of exquisite precision with which to measure the change of the characteristics of the mutual orbit of the two stars.