Psr B1919 21

PSR B1919+21
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Vulpecula
Right ascension 19h 21m 44.79808s[1]
Declination +21° 53′ 01.8288″[1]
Evolutionary stagePulsar
Distance2283.12 ly
Mass~1.4 M
Radius~1.4 × 10-6 R
Luminosity0.006[2] L
Age16[2] Myr
Other designations
PSR J1921+2153, PSR 1921+2153, PSR B1919+21, PSR 1919+21, WSTB 12W15, PULS CP 1919+21, PULS CP 1919, CP 1919+21, CP 1919

PSR B1919+21 is a pulsar with a period of 1.3373 seconds,[3] and a pulse width of 0.04 second. It was the first radio pulsar discovered (in July 1967 by Jocelyn Bell Burnell and Antony Hewish). The power and regularity of the signals was thought to resemble a beacon, so for a time the source was nick-named "LGM-1" (for "Little Green Men").

The original designation of this pulsar was CP 1919 and it is also known as PSR J1921+2153. It is located in the constellation of Vulpecula.

LGM-1 discovery

Little green men 1 (LGM-1) was the explanation given to a certain astronomical observation. In 1967, a radio signal was detected in a UK observatory by Jocelyn Bell and Antony Hewish. The signal had a 1.337302088331 second period and 0.04 second pulsewidth.[3] It originated at celestial coordinates 19h 19m right ascension, +21° declination. 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, but this hypothesis was promptly discarded. After that, the discoverers proposed an alternative explanation that the signal might be a beacon or a communication from an intelligent extraterrestrial civilization and named it LGM-1 (LGM = "Little Green Men").

The signal turned out to be radio emissions from the pulsar CP1919, the first one recognized as such. Bell noted that other scientists could have discovered pulsars before her, but their observations were either ignored or disregarded. Researchers Thomas Gold and Sir Fred Hoyle identified this astronomical object as a rapidly rotating neutron star immediately upon their announcement.

Before the nature of the signal was determined, the researchers, Bell and her Ph.D supervisor Antony Hewish, somewhat seriously 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?[4]

Nobel Prize controversy

When Hewish and Martin Ryle received the Nobel Prize in physics in 1974 for their work in radio-astronomy and pulsars, Hoyle argued that Bell Burnell should have been a co-recipient of the prize.[5]

Cultural reference

The British post-punk band Joy Division used an image of CP 1919's radio pulses on the cover of their debut album, Unknown Pleasures.[6][7]

See also


Further reading

External links

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.