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PSR B1919+21 is a
pulsar A pulsar (from ''pulsating radio source'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Ea ...
with a period of 1.3373 seconds and a pulse width of 0.04 seconds. Discovered by
Jocelyn Bell Burnell Dame Susan Jocelyn Bell Burnell (; Bell; born 15 July 1943) is an astrophysicist from Northern Ireland who, as a postgraduate student, discovered the first radio pulsars in 1967. The discovery eventually earned the Nobel Prize in Physics in ...
on 28 November 1967, it is the first discovered radio pulsar. The power and regularity of the signals were briefly thought to resemble an extraterrestrial
beacon A beacon is an intentionally conspicuous device designed to attract attention to a specific location. A common example is the lighthouse, which draws attention to a fixed point that can be used to navigate around obstacles or into port. More mode ...
, leading the source to be nicknamed LGM, later LGM-1 (for "
little green men Little green men is the stereotypical portrayal of extraterrestrials as little humanoid creatures with green skin and sometimes with antennae on their heads. The term is also sometimes used to describe gremlins, mythical creatures known for cau ...
"). The original designation of this pulsar was CP 1919, which stands for Cambridge Pulsar at RA . It is also known as PSR J1921+2153 and is located in the
constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellation ...
of
Vulpecula Vulpecula is a faint constellation in the northern sky. Its name is Latin for "little fox", although it is commonly known simply as the fox. It was identified in the seventeenth century, and is located in the middle of the Summer Triangle (an ...
.


Discovery

In 1967, a radio signal was detected using the
Interplanetary Scintillation Array The Interplanetary Scintillation Array (also known as the IPS Array or Pulsar Array) is a radio telescope that was built in 1967 at the Mullard Radio Astronomy Observatory, in Cambridge, United Kingdom, and was operated by the Cavendish Astrop ...
of the
Mullard Radio Astronomy Observatory The Mullard Radio Astronomy Observatory (MRAO) is located near Cambridge, UK and is home to a number of the largest and most advanced aperture synthesis radio telescopes in the world, including the One-Mile Telescope, 5-km Ryle Telescope, an ...
in
Cambridge Cambridge ( ) is a university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge bec ...
, UK, by Jocelyn Bell Burnell. The signal had a -second
period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...
and 0.04-second pulsewidth. It originated at
celestial coordinate Astronomical coordinate systems are organized arrangements for specifying positions of satellites, planets, stars, galaxies, and other celestial objects relative to physical reference points available to a situated observer (e.g. the true horizon ...
s
right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the ( hour circle of the) point in question above the earth. When pair ...
, +21°
declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of th ...
. It was detected by individual observation of miles of graphical data traces. Due to its almost perfect regularity, it was at first assumed to be spurious
noise Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference aris ...
, but this hypothesis was promptly discarded. The discoverers jokingly named it ''little green men 1'' (''LGM-1''), considering that it may have originated from an extraterrestrial civilization, but Bell Burnell soon ruled out extraterrestrial life as a source after discovering a similar signal from another part of the sky. The original signal turned out to be radio emissions from the pulsar CP 1919, and was the first one recognized as such. Bell Burnell noted that other scientists could have discovered pulsars before her, but their observations were either ignored or disregarded. Researchers
Thomas Gold Thomas Gold (May 22, 1920 – June 22, 2004) was an Austrian-born American astrophysicist, a professor of astronomy at Cornell University, a member of the U.S. National Academy of Sciences, and a Fellow of the Royal Society (London). Gold was ...
and
Fred Hoyle Sir Fred Hoyle FRS (24 June 1915 – 20 August 2001) was an English astronomer who formulated the theory of stellar nucleosynthesis and was one of the authors of the influential B2FH paper. He also held controversial stances on other sci ...
identified this astronomical object as a rapidly rotating
neutron star A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. w ...
immediately upon their announcement. Before the nature of the signal was determined, the researchers, Bell Burnell and her PhD supervisor
Antony Hewish Antony Hewish (11 May 1924 – 13 September 2021) was 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. He was also awarded th ...
, considered the possibility of extraterrestrial life:
We did not really believe that we had picked up signals from another civilization, but obviously the idea had crossed our minds and we had no proof that it was an entirely natural radio emission. It is an interesting problem – if one thinks one may have detected life elsewhere in the universe how does one announce the results responsibly? Who does one tell first?


Nobel Prize controversy

When Antony Hewish and
Martin Ryle Sir Martin Ryle (27 September 1918 – 14 October 1984) was an English radio astronomer who developed revolutionary radio telescope systems (see e.g. aperture synthesis) and used them for accurate location and imaging of weak radio sourc ...
received the
Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
in physics in 1974 for their work in
radio astronomy Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation comin ...
and pulsars,
Fred Hoyle Sir Fred Hoyle FRS (24 June 1915 – 20 August 2001) was an English astronomer who formulated the theory of stellar nucleosynthesis and was one of the authors of the influential B2FH paper. He also held controversial stances on other sci ...
, Hewish's fellow astronomer, argued that Jocelyn Bell Burnell should have been a co-recipient of the prize. In 2018, Bell won the $3-Million
Breakthrough Prize in Fundamental Physics The Breakthrough Prize in Fundamental Physics is one of the Breakthrough Prizes, awarded by the Breakthrough Prize Board. Initially named Fundamental Physics Prize, it was founded in July 2012 by Russia-born Israeli entrepreneur, venture c ...
for her work.


Cultural references

The English
post-punk Post-punk (originally called new musick) is a broad genre of punk music that emerged in the late 1970s as musicians departed from punk's traditional elements and raw simplicity, instead adopting a variety of avant-garde sensibilities and non-r ...
band
Joy Division Joy Division were an English rock band formed in Salford in 1976. The group consisted of vocalist Ian Curtis, guitarist/keyboardist Bernard Sumner, bassist Peter Hook and drummer Stephen Morris. Sumner and Hook formed the band after atte ...
used an image of CP 1919's radio pulses on the cover of their 1979 debut album, ''
Unknown Pleasures ''Unknown Pleasures'' is the debut studio album by English rock band Joy Division, released on 15 June 1979 by Factory Records. The album was recorded and mixed over three successive weekends at Stockport's Strawberry Studios in April 1979, wi ...
''. German-born British composer
Max Richter Max Richter (; ; born 22 March 1966) is a German-born British composer and pianist. He works within postminimalist and contemporary classical styles. Richter is classically trained, having graduated in composition from the University of Edinburg ...
wrote a piece inspired by the discovery of CP1919 titled ''Journey (CP1919)''. The English
indie rock Indie rock is a subgenre of rock music that originated in the United States, United Kingdom and New Zealand from the 1970s to the 1980s. Originally used to describe independent record labels, the term became associated with the music they produ ...
band
Arctic Monkeys Arctic Monkeys are an English rock band formed in Sheffield in 2002. The group consists of Alex Turner (lead vocals, guitar, keyboards), Jamie Cook (guitar, keyboards), Nick O'Malley (bass guitar, backing vocals), and Matt Helders (drums, ...
used a sound based on the pulses in their music video for "
Four Out of Five "Four Out of Five" is a song by English indie rock band Arctic Monkeys. It was released as the lead single from their sixth studio album, ''Tranquility Base Hotel & Casino'' (2018), on 13 May 2018, with an accompanying music video. Composition ...
." from 0:05-1:16


See also

*
Variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...


References


Further reading

* * *


External links

* * {{DEFAULTSORT:PSR B1919+21 Rotation-powered pulsars Vulpecula Astronomical objects discovered in 1967
LGM-1 PSR B1919+21 is a pulsar with a period of 1.3373 seconds and a pulse width of 0.04 seconds. Discovered by Jocelyn Bell Burnell on 28 November 1967, it is the first discovered radio pulsar. The power and regularity of the signals were ...