Jocelyn Bell Burnell and the Discovery of Pulsars

A composite image of the Crab Nebula showing the X-ray (blue), and optical (red) images superimposed.

On November 28, 1967, Jocelyn Bell Burnell and Anthony Hewish discovered the first Pulsar, a fast rotating neutron star that emits a beam of electromagnetic radiation. The radiation of a pulsar can only be observed when the beam of emission is pointing toward the Earth, much the way a lighthouse can only be seen when the light is pointed in the direction of an observer, and is responsible for the pulsed appearance of emission.

In 1967, Jocelyn Bell Burnell and Professor Antony Hewish began to analyse the results of the radio telescope, which they had put up to search for radio signals from quasars. Bell Burnell noticed pulses from the same location recurring in short periods, wherefore sources like regular stars could be excluded. Also, the pulses followed sidereal time, and therefore it was clear that these interferences could not have been man-made. Due to these facts, Bell Burnell and Hewish named the strange signal LGM-1 (Little Green Man), since they could neither prove nor disprove the signal’s source coming from an extraterrestrial civilization. After another pulsating source was discovered, both scientists abandoned the LGM-theory and the pulsar was later renamed into CP 1919. Hewish and Bell Burnell also described the pulsar being a “novel type between a white dwarf and a neutron”, which was supported by the astrophysicists Thomas Gold (a colleague of the famous Fred Hoyle) and Franco Pacini a year after its discovery.

In the following years, further pulsars were detected. The discovery of a pulsar in a binary system in 1974 was special due to the fact that it provided evidence of the existence of gravitational waves with the help of Einstein‘s theory of general relativity. Don Backer discovered almost a decade later a pulsar with an extraordinary short rotation period of only 1.6 milliseconds, wherefore the new class of millisecond pulsars was found.

But, coming back to the pulsar discovery of 1967, Anthony Hewish was awarded the Nobel Price of Physics for his achievements on the pulsar, while Jocelyn Bell Burnell wasn’t. Bell Burnell worked, after finishing her Ph.D degree at the University of Southhampton, at the University College London, the Royal Observatory of Edinburgh, and was highly active as a tutor and lecturer for the Open University. She was later teaching at Princeton University and President of the Royal Astronomical Society.

At yovisto you can watch Professor Dame Jocelyn Bell Burnell herself introducing the pulsing radio stars she discovered as a doctoral student.

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