Blog 13: Cecilia Payne-Gaposhkin

Cecilia Payne-Gaposhkin was one of astronomy's most influential researches of the 20th century. Her accomplishments are extremely relevant both to the astronomy we study and to paving the way for female astronomers here at Harvard. 

A portrait Payne-Gaposhkin, which resides on campus at the Harvard Art Museums
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Cecilia Payne-Gaposhkin was born in 1900 in Wendover England. She studied natural sciences and botany at Newham College. However, she was so inspired by the work of Arthur Eddington - she had memorized his lecture and could write it verbatim - she switched to the field of astronomy.

In 1919, she came to Radcliffe college with a fellowship designed to encourage women in science at Radcliffe. She went on to receive the first P.h.D. in astronomy from Radcliffe in just two years. Her thesis was described by Otto Struve as "the most brilliant P.h.D. thesis in astronomy." Her work disproved the currently accepted idea that stars are composed of elements similar to Earth. Instead she showed that differences in stellar spectra come from different levels of ionization due to different temperatures, not different chemical compositions. The seven different spectra seen in stars were thought to be different chemical compositions. However, she proposed that due to the hot environments of stars, ions were forming in variable amounts at variable temperatures. This explained the distinct emission spectrum of star types, rather than the idea that there are seven compositionally distinct classes of star. Furthermore, by studying these spectral lines, Payne-Gaposhkin discovered that the abundance of hydrogen and helium is significantly higher in stars than on Earth. The seven different emission patterns perfectly fit with emissions from seven different groups of hydrogen ions, each of which exist in unique temperature ranges. This work paved the way for our modern understanding on element creation via fusion and fission in stars. 

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However, her work remained unpublished for years after her dissertation reviewer, astronomer Henry Russell, discouraged her from presenting the findings, as they were too contrary to the accepted cannon. Despite this, Russell published similar findings a few years later and received credit for the discovery.

This did not stop Payne-Gaposhkin. She continued on to study stars of high luminosity, in order to understand the structure of the Milky Way. Additionally, under her direction, 1.25 million observations were made of variable stars, and if that was not enough, another two million observations were made in her study of Magellanic clouds. 

By the end of her life, Payne-Gaposhkin published over 150 papers and recieved an Annie Cannon (another great female astronomer at Harvard) award in 1934. Not only did she recieve the first P.h.D. in astronomy at Radcliffe, she also became the first female full professor in Harvard's Faculty of Arts and Sciences and the first female head of a department at Harvard. Cecilia Payne-Gaposhkin led the way for many astronomers today.

Sources:

http://www.sheisanastronomer.org/index.php/history/cecilia-payne-gaposchkin

http://www.epigenesys.eu/en/science-and-you/women-in-science/808-cecilia-payne-gaposchkin

http://astrogeo.oxfordjournals.org/content/43/1/1.27.full

https://www.youtube.com/watch?v=I_qF-jTY2zY