Composite Optical/X-ray image of the Crab Nebula pulsar, showing surrounding nebular gases stirred by the pulsar's magnetic field and radiation.

A rotation-powered pulsar is a rapidly rotating neutron star, whose electromagnetic radiation is observed in regularly spaced intervals, or pulses. It differs from other types of pulsars in that the source of power for the production of radiation is the loss of rotational energy. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... Messier Object 1, the Crab Nebula. ... Cross section of a neutron star A neutron star is a type of degenerate star composed mostly of densely packed neutrons, generally about 25 km in diameter and as massive as an average star. ... Klystrons give off both ionizing and electromagnetic radiation. ... Composite Optical/X-ray image of the Crab Nebula pulsar, showing surrounding nebular gases stirred by the pulsars magnetic field and radiation. ... Rotating objects contain kinetic energy. ...

As the first type of pulsars to be discovered, rotation-powered pulsars were originally known simply as pulsars, a term coined by a Daily Telegraph journalist as a contraction of "pulsating star". Although it was soon learned that the pulses were related to rotation rather than to physical expansion and contraction, as in true pulsating variable stars, the term stuck. After the discovery of accretion-powered x-ray pulsars, rotation-powered pulsars were known as radio pulsars. Since there are now rotation-powered pulsars known that emit x-rays but not radio waves, the term "rotation-powered pulsar" is preferred. This article deals with The Daily Telegraph in Britain, see The Daily Telegraph (Australia) for the Australian publication The Daily Telegraph is a British broadsheet newspaper founded in 1855. ... Most stars are of nearly constant luminosity. ... Accretion, means any growth or increase in size by a gradual external addition or inclusion. ... An X-ray pulsar is a neutron star with a powerful magnetic field that gives rise to regular X-ray pulses. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. ...

History

The first known pulsar was discovered by Jocelyn Bell and Antony Hewish in 1967 while they were using a radio array to study the scintillation of quasars. They found a very regular signal, consisting of pulses of radiation at a rate of one in every few seconds. Terrestrial origin of the signal was ruled out because the time it took the object to reappear was a sidereal day instead of a solar day. Jocelyn Bell Burnell (born Jocelyn Bell, 15 July 1943), British astrophysicist who discovered the first radio pulsars with her thesis advisor Antony Hewish. ... Antony Hewish (born Fowey, Cornwall, May 11, 1924) is a British radio astronomer who won the Nobel Prize for Physics in 1974 (together with fellow radio-astronomer Martin Ryle) for his role in the discovery of pulsars. ... 1967 was a common year starting on Sunday of the Gregorian calendar. ... This view, taken with infrared light, is a false-color image of a quasar-starburst tandem with the most luminous starburst ever seen in such a combination. ... On a prograde planet like the Earth, the sidereal day is shorter than the solar day. ... Solar time is based on the idea that when the sun reaches its highest point in the sky, it is noon. ...

The original name given to the object was "LGM-1", short for "Little Green Men", a comical name for intelligent beings of extraterrestrial origin. Although this choice of naming is indicative of the mystery surrounding the origin of the signals, according to Martin Rees, the hypothesis that they were beacons from extraterrestrial civilisations were never taken very seriously. The suggestion that pulsars were rotating neutron stars was put forth independently by Thomas Gold and Franco Pacini in 1968, and was soon proven beyond doubt by the discovery of a pulsar with a very short 33-millisecond pulse period in the Crab nebula. Little green men is a popular expression used to describe extraterrestrial life. ... The existence of extraterrestrial life remains hypothetical though human beings continue to search Extraterrestrial life is life that may exist and originate outside our planet Earth. ... Sir Martin John Rees, FRS (born 23 June 1942) is a professor of astronomy. ... Thomas Gold (May 22, 1920 – June 22, 2004) was an Austrian astrophysicist, a professor of astronomy at Cornell University, and a member of the US National Academy of Sciences. ... 1968 was a leap year starting on Monday (the link is to a full 1968 calendar). ... A millisecond is an SI-derived unit of time, equal to one thousandth of a second. ... Messier Object 1, the Crab Nebula. ...

In 1974, Antony Hewish was awarded the Nobel Prize in physics, the first astronomer to do so (astronomer Martin Ryle also received the prize this year). Considerable controversy is associated with the fact that Professor Hewish was awarded the prize while Bell, who made the initial discovery while she was a PhD student, was not. 1974 is a common year starting on Tuesday (click on link for calendar). ... List of Nobel Prize laureates in Physics from 1901 to the present day. ... Sir Martin Ryle (September 27, 1918 – October 14, 1984) was a British radio astronomer who developed revolutionary radio telescope systems (see e. ...

Also in 1974, Joseph Taylor and Russell Hulse discovered for the first time a pulsar in a binary system. This pulsar orbits another neutron star with an orbital period of just eight hours. Einstein's theory of general relativity predicts that this system should emit strong gravitational radiation, causing the orbit to continually contract as it loses orbital energy. Observations of the pulsar soon confirmed this prediction, providing the first ever proof of the existence of gravitational waves. As of 2004, observations of this pulsar continue to agree with general relativity. In 1993 the Nobel prize in physics was awarded to Taylor and Hulse for the discovery of this pulsar. 1974 is a common year starting on Tuesday (click on link for calendar). ... Joseph H. Taylor, Jr. ... Russell Alan Hulse (born November 28, 1950) is an American physicist and winner of the Nobel Prize in Physics, shared with his thesis advisor Joseph Hooton Taylor Jr. ... A binary star system consists of two stars both orbiting around their barycenter. ... For other topics related to Einstein see Einstein (disambiguation). ... Two-dimensional visualization of space-time distortion. ... In physics, a gravitational wave consists of energy transmitted in the form of a wave through the gravitational field of space-time. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... 2004(MMIV) is a leap year starting on Thursday of the Gregorian calendar. ... 1993 is a common year starting on Friday of the Gregorian calendar and marked the Beginning of the International Decade to Combat Racism and Racial Discrimination (1993-2003). ...

In 1982, a pulsar with a rotation period of just 1.6 milliseconds was discovered, by Shri Kulkarni and Don Backer. Observations soon revealed that its magnetic field was much weaker than ordinary pulsars, while further discoveries cemented the idea that a new class of object, "millisecond pulsars" (MSPs) had been found. MSPs are believed to be the end product of X-ray binaries. Owing to their extrordinarily rapid and stable rotation, MSPs can be used by astronomers as clocks rivalling the stability of the best atomic clocks on Earth. Factors affecting the arrival time of pulses at the Earth by more than a few hundred nanoseconds can be easily detected and used to make precise measurements. Physical parameters accessible through pulsar timing include the three-dimensional position of the pulsar, its proper motion, the electron content of the interstellar medium along the propagation path, the orbital parameters of any binary companion, the pulsar rotation period and its evolution with time. Once these factors have been taken into account, deviations between the observed arrival times and predictions made using these parameters can be found and attributed to one of three possibilities: intrinsic variations in the spin period of the pulsar, errors in the realization of Terrestrial Time against which arrival times were measured, or the presence of background gravitational waves. Scientists are currently attempting to resolve these possibilities by comparing the deviations seen amongst several different pulsars, forming what is known as a Pulsar Timing Array. With luck, these efforts may lead to a time scale a factor of ten or more better than currently available, and the first ever direct detection of gravitational waves. 1982 is a common year starting on Friday of the Gregorian calendar. ... X-ray binaries are a class of binary stars that are very luminous in X-rays. ... An astronomer or astrophysicist is a scientist whose area of research is astronomy or astrophysics. ... An atomic clock is a type of clock that uses an atomic resonance frequency standard as its counter. ... A nanosecond is an SI derived unit of time equal to 10-9 of a second. ... The proper motion of a star is the motion of the position of the star in the sky (the change in direction in which we see it, as opposed to the radial velocity) after eliminating the improper motions of the stars, which affect their measured coordinates but are not real... Properties The electron is a fundamental subatomic particle which carries a negative electric charge. ... In astronomy, the interstellar medium (or ISM) is the matter and energy content that exists between the stars (or their immediate circumstellar environment) within a galaxy. ... This article is about terrestrial time; for other meanings of TT, see TT (disambiguation). ... A time scale specifies divisions of time. ...

The first ever detected extrasolar planets were found orbiting a millisecond pulsar in 1990, by Aleksander Wolszczan. This discovery presented important evidence concerning the widespread existence of planets outside the solar system, although it is very unlikely that any life form could survive in the environment of intense radiation near a pulsar. Infrared Image of a possible extrasolar planet (lower left) in the Constellation Taurus, taken by the Hubble Space Telescope. ... 1990 is a common year starting on Monday of the Gregorian calendar. ... Aleksander Wolszczan (b. ... Presentation of the solar system (not to scale) The solar system is the retinue of objects gravitationally bound to our Sun. ... Lifeform is the physical entity which encompasses a life. ...

Theory

There is general agreement that what we observe as a pulse is what happens when a beam of radiation points in our direction, once for every rotation of the neutron star. The origin of the beam is related to the misalignment of the rotation axis and the axis of the magnetic field of the star. The beam is emitted from the poles of the neutron star's magnetic field, which may be offset from the rotational poles by a wide angle. The source of energy of the beam is the rotational energy of the neutron star. The rotation slows down over time as the energy is emitted. Current flowing through a wire produces a magnetic field (M) around the wire. ...

Millisecond pulsars are thought to have been spun up to high rotational speed by infalling matter pulled off of a companion star.

Of interest to the study of the state of the matter in a neutron stars are the glitches observed in the rotation velocity of the neutron star. This velocity is decreasing slowly but steadily, except by sudden variations. These were for a time believed to be "starquakes" due to the adjustment of the crust of the neutron star. Models where the glitch is due to a decoupling of the possibly superconducting interior of the star have also been advanced. A magnet levitating above a high-temperature superconductor (100. ...

In 2003 observations of the Crab nebula pulsar's signal revealed "sub-pulses" within the main signal with durations of only nanoseconds. It is thought that these nanosecond pulses are emitted by regions on the pulsar's surface 60cm in diameter or smaller, making them the smallest structures outside the solar system to be measured. 2003(MMIII) is a common year starting on Wednesday of the Gregorian calendar. ... Messier Object 1, the Crab Nebula. ...

Importance

As mentioned above, the discovery of pulsars allowed astronomers to study an object never observed before, the neutron star. This kind of object is the only place where the behaviour of matter at nuclear density can be observed (though not directly). Also, millisecond pulsars have allowed one test of general relativity in conditions of an intense gravitational field. Cross section of a neutron star A neutron star is a type of degenerate star composed mostly of densely packed neutrons, generally about 25 km in diameter and as massive as an average star. ... A stylized representation of a lithium atom. ... Two-dimensional visualization of space-time distortion. ...

Significant pulsars

• The first radio pulsar, CP 1919 (now known as PSR B1919+21), with a pulse period of 1.337 seconds and a pulse width of 0.04 second, was discovered in 1967. A drawing of this pulsar's radio waves was used as the cover of British rock band Joy Division's debut album, "Unknown Pleasures".
• The first binary pulsar, PSR B1913+16, confirming general relativity and proving the existence of gravitational waves
• The first millisecond pulsar, PSR B1937+21
• The first pulsar with planets, PSR B1257+12
• The first double pulsar binary system, PSR J0737−3039
• The longest period pulsar, PSR J2144−3933

The first radio pulsar, CP 1919, with a pulse period of 1. ... The first radio pulsar, CP 1919, with a pulse period of 1. ... 1967 was a common year starting on Sunday of the Gregorian calendar. ... Joy Division was a rock music band formed in 1977 in Manchester, England. ... Unknown Pleasures is the first album by Joy Division, released in 1979. ... The title given to this article is incorrect due to technical limitations. ... Artists impression. ... PSR J2144-3933 is a pulsar about 180 parsecs (5. ...

See Also

• Neutron star
• Pulsar
• Radio pulsar
• X-ray pulsar
• Magnetar
• Millisecond pulsar
• Pulsar planets
• List of pulsars