PSR B1919 21

PSR B1919 21 is the first pulsar discovered. It has a period of 1.337 s It is located in the constellation Vulpecula ( Vulpecula ) in right ascension and declination 19h19m16s 21 ° 47 ', and is about 2,000 light -years from the solar system.

Properties

PSR B1919 21 emits radio waves in the frequency range from 85 MHz to 2.7 GHz. The period of the pulsar is 1.337301192269 seconds and decreases by 1.34809 × 10 - 15s per second. The pulse length measures 0.04 s

Discovery history

PSR B1919 21 was discovered in 1967 by graduate student Jocelyn Bell. With her thesis supervisor Antony Hewish, she examined scintillations (apparent change in the radiation intensity) of radio signals to detect quasars. Since quasars are compact radio sources, the scintillation is with them more pronounced than with extended objects. Hewish had for this purpose a radio telescope at Cambridge University designed and built. This telescope - it was taken in July 1967 in Operation - produced daily about 30 meters data sheets that were evaluated manually by Bell. In the summer of 1967 she discovered in the recorded radio signals atypical fluctuations, which held Hewish first to interference from passing cars - also possible signal reflections from the moon or from satellites that could have upset the delicate telescope were taken and analyzed in consideration.

The regularity of the pulses and the short period of a little more than a second at first seemed to point to a non-natural cause. Since Hewish and Bell calculated that the source is located outside the solar system, but still within the Milky Way, but they still they assumed that the signals were artificial in origin, they moved the discovery of an alien intelligence into account. They christened the source therefore internally on the name " LGM -1" ( "Little Green Man 1", an unofficial designation that has been used for the first pulsars ), officially received the designation CP 1919, which Cambridge pulsar with α = means 19h19m.

Had the signals actually been sent by aliens, they would have according to Doppler effect must have a spectral shift as the planet of aliens would like the earth move around a star must. However, it could not be detected Doppler effect, so that the extraterrestrial source could be excluded. As Hewish published the results so far in February 1968, was not always clear which object sent out the radio pulses. Ultimately, astronomers reported Franco Pacini and Thomas Gold theoretically after that it is the pulsar is a neutron star - a first since 1934 hypothetically known object.

Nobel Prize award

For the discovery of the pulsar Antony Hewish was awarded the Nobel Prize for Physics in 1974. Jocelyn Bell was not included in the award - a decision that was quite controversial at the time.

Cultural processing

The British post-punk band Joy Division used a picture of the radio pulses from this pulsar as a cover for their debut album Unknown Pleasures.