Jocelyn Burnell - her discovery of pulsars

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Burnell discovered pulsars, which are rapidly rotating neutron stars that emit radio-frequency pulses, on November 28, 1967. 

  • Neutron stars are the result of a supernova explosion, which is when a star reaches the end of its life and dies
  • Jocelyn Burnell was the president of the Royal Astronomical Society from 2002-2004 and was the first woman to hold the office of the president of the Royal Society of Edinburgh from 2014-2018.
  • Burnell discovered pulsars, which are rapidly rotating neutron stars that emit radio-frequency pulses, on November 28, 1967. 
  • The discovery was recognised by a Nobel Prize in physics in 1974 that was shared by two professors, Antony Hewish (Burnell’s supervisor) and Martin Ryle.
  • Discovering a pulsar using a vast radio telescope occupying an area of 4.5 acres that was designed by Hewish and joined him and the team of five when the construction of the telescope was about to begin. 
  • As per Burnell, she had the sole responsibility of operating the telescope and analysing its data output, which amounted to 96-feet of chart paper everyday.

 

Pulsars

  • A pulsar is a highly magnetized rotating compact star (usually neutron stars but also white dwarfs) 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 Earth (much like the way a lighthouse can be seen only when the light is pointed in the direction of an observer), and is responsible for the pulsed appearance of emission. 
  • Neutron stars are very dense, and have short, regular rotational periods.
  • This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. 
  • Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays (see also centrifugal mechanism of acceleration).
  • The periods of pulsars make them very useful tools for astronomers. Observations of a pulsar in a binary neutron star system were used to indirectly confirm the existence of gravitational radiation
  • The first extrasolar planets were discovered around a pulsar, PSR B1257+12. In 1983, certain types of pulsars were detected that at that time exceeded atomic clocks in their accuracy in keeping time.
  • The events leading to the formation of a pulsar begin when the core of a massive star is compressed during a supernova, which collapses into a neutron star. 
  • The neutron star retains most of its angular momentum, and since it has only a tiny fraction of its progenitor's radius (and therefore its moment of inertia is sharply reduced), it is formed with very high rotation speed. 
  • A beam of radiation is emitted along the magnetic axis of the pulsar, which spins along with the rotation of the neutron star. 
  • The magnetic axis of the pulsar determines the direction of the electromagnetic beam, with the magnetic axis not necessarily being the same as its rotational axis. 
  • This misalignment causes the beam to be seen once for every rotation of the neutron star, which leads to the "pulsed" nature of its appearance.
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