Susan Jocelyn Bell Burnell

views updated

Susan Jocelyn Bell Burnell

The radio astronomer Susan Jocelyn Bell Burnell (born 1943) discovered the first pulsar (stars that release regular bursts of radio waves) in 1967.

Susan Jocelyn Bell (Burnell) was born in Belfast, Northern Ireland, on July 15, 1943. Her father was the architect for the Armagh Observatory, which was close to their home. Her early interest in astronomy was encouraged by the observatory staff.

She studied at the Mount School in York, England, from 1956 to 1961. She earned a B.S. in physics at the University of Glasgow in 1965. That same year, she began work on her Ph.D. at Cambridge University. There, under the supervision of Antony Hewish, she constructed and operated a 81.5 megaherz radio telescope. She studied interplanetary scintillation of compact radio sources.

Bell Burnell detected the first four pulsars. The term "pulsar" is an abbreviation of pulsating radio star or of rapidly pulsating radio sources. Pulsars represent rotating neutron stars that emit brilliant flashes of electromagnetic radiation at each revolution, like beacons from a lighthouse. The observation of pulsars requires the use of radio telescopes. In 15 years, about 350 pulsars were found. Their pulse periods range from 33 microseconds to 4 seconds. A "fast" pulsar was discovered in 1982. Its short pulse period equals 1.5 microseconds. According to Joseph H. Taylor, Jr., "it has become clear that hundreds of thousands of pulsars must exist in the Milky Way Galaxy—most of them too distant to be detected with existing radio telescopes.

Discovery of Pulsar

For two years, Bell Burnell constructed the radio telescope which she would begin to operate in July 1967. Each complete coverage of the sky with the radio telescope required four days. Bell Burnell then had to analyze about 400 feet of paper chart. She noted: "We analyzed (actually, we didn't, I analyzed) all this chart by hand." The signal of the pulsar occupied about half an inch of the 400 feet of chart.

For the first time in the history of radio astronomy, a large area of the sky had been repeatedly surveyed with an extremely sensitive radio telescope tuned to meter wavelengths. The subsequent discovery of the pulsar, in 1967, ranks as an important milestone in the history of astrophysics. It has been written that "In an earlier age the pulsar would no doubt have been called 'Bell's star'; today it is simply known as CP 1919." "CP" stands for "Cambridge pulsar." The pulsars appeared as an appendix to Bell Burnell's Ph.D. thesis.

In 1947 Sir Martin Ryle and Tony Hewish, from the Cavendish Laboratory in Cambridge, England, were jointly awarded the Nobel Prize in physics, with Hewish honored for the discovery of pulsars. This was the first time the prize was given for work in observational astronomy. The Nobel Prize announcement triggered a public controversy. Sir Fred Hoyle, the eminent British astronomer, argued that Bell Burnell should have shared the Nobel Prize.

Radio Astronomy Work

Bell Burnell held a Science Research Council fellowship from 1968 to 1970 and a junior teaching fellowship from 1970 to 1973 at the University of Southampton. During that time she studied the mid-latitude electron density trough in the topside ionosphere using data from the Alouette satellite, the enhancements of interplanetary scintillation, and their relationship to co-rotating streams in the interplanetary medium and to Forbush decreases. She developed and calibrated a 1-10 million electron volts gamma-ray telescope.

She was employed as a researcher at the Mullard Space Science Laboratory at the University College in London; as a graduate programmer from 1974 to 1976, then as an associate research follow from 1976 to 1982. She analyzed data from a rocket flight to study low energy x-ray emission from galactic features. With the x-ray spectrometer on the Ariel V satellite she observed galactic sources, including transient x-ray sources and binary star systems, globular clusters, active galaxies, and clusters of galaxies.

After 1982 Bell Burnell worked as a senior research fellow at the Royal Observatory in Edinburgh, Scotland. There she made infrared observations of galaxies with active nuclei coordinated with radio, optical, ultraviolet, and x-ray observations. She also observed infrared counterparts of galactic x-ray sources.

Bell Burnell was the editor of The Observatory from 1973 to 1976. Elected a fellow of the Royal Astronomical Society in 1969, she became a council member from 1978 to 1981. She was elected a member of the International Astronomical Union in 1979 and served on the Science and Engineering Research Council, Astronomy I Committee from 1978 to 1984.

Bell Burnell has received numerous awards for her professional contributions. In 1973 she received (jointly with Hewish), the Michelson Medal by the Franklin Institute in Philadelphia. In 1978 she was awarded the J. Robert Oppenheimer Memorial Prize from the Center for Theoretical Studies in Miami. In 1978 she was also given the Rennie Taylor Award by the American Tentative Society in New York. She received the Beatrice M. Tinsley Prize from the American Astronomical Society in 1987 and the Herschel Medal from the Royal Astronomical Society in 1989.

Bell Burnell was married in 1968 and has one son. In 1997 she headed the Physics Department at Open University in the United Kingdom.

Further Reading

A short biography of Bell Burnell appeared in John Daintith et al., Chambers Biographical Encyclopaedia of Scientists (1983). The first article on the pulsar, "Observation of a Rapidly Pulsating Radio Source, " was published by Antony Hewish, Bell Burnell, J. D. H. Pilkington, P. F. Scott, and R. A. Collins in Nature (February 24, 1968). On the discovery of pulsars, see the paper by Bell Burnell, "The Discovery of Pulsars, " in Serendipitous Discoveries in Radio Astronomy, edited by K. Kellermann and B. Sheets (1984). The chronology of the discovery is discussed by S. W. Woolgar in "Writing an Intellectual History of Scientific Development: The Use of Discovery Accounts" in Social Studies of Science (September 1976). The Nobel Prize controversy is detailed in Nicholas Wade, "Discovery of Pulsars: A Graduate Student's Story" (News and Comment) in Science (August 1, 1975). On pulsars, see Antony Hewish, "Pulsars" in Scientific American (October 1968); A. Hewish "Pulsars and High Density Physics" Science (June 13, 1975); Joseph H. Taylor, Jr., "Pulsar, " in McGraw-Hill Encyclopedia of Science and Technology (1982); Donald Backer and Shrinivas Kulkarni, "Pulsar, " in McGraw-Hill Yearbook of Science and Technology (1984). Further Information on Bell Burnell can be found in David E. Fisher's The Origin and Evolution of Our Own Particular Universe's Cosmic Wormholes: The Search for Interstellar Shortcuts (1992). Information about Bell Burnell's academic career can be accessed on the Internet through the Open University Physics Department's Web site at <> (July 29, 1997). □