Wednesday, February 19, 2014

Cecilia Payne-Gaposchkin

There are a lot of neat people stories in the history of science. I've recently been interested in women astronomers who made major advances but are not as well known as the big 3: Caroline Herschel, Annie Jump Cannon and Henrietta Swan Leavitt. This month I am writing about Cecilia Payne-Gaposchkin (1900-1979) who stuck with her convictions to make big discoveries on the nature of stars. She has a really nice autobiography called "The Dyers Hand" (published in the collection "Cecilia Payne-Gaposchkin: An Autobiography and Other Recollections") which I found in the Stanford stacks during a recent visit.

Cecilia Payne grew up in Britain and went to University of Cambridge. There, a class by Eddington inspired her to pursue astronomy. Eddington encouraged her to go to the US where there were more opportunities for women. She applied to Harvard and received a fellowship for graduate studies with Shapley.

There was a long tradition at Harvard of using spectroscopy to study the abundances and temperatures of stars.  The O, B, A, … classification scheme was developed there.  In her 1925 PhD thesis with Shapley (from Radcliffe because Harvard would not grant the degree to a woman, she was the first astronomy PhD from Radcliffe), Payne was able to relate the stellar classification scheme to the surface temperatures of stars.  Most importantly, she showed that hydrogen and helium are the dominant elements that make up stars.  This seems obvious to us now, but was contrary to the belief at that time that the sun had the same abundances as the Earth.  She had a disagreement about this with the prominent astronomer Russell.   In fact, he persuaded her to add a note in her paper that the H, He result was "almost certainly not real".  In 1929 he acknowledged that she was correct and cited her work in his further papers.

During the 1930's and 1940's Payne was a lecturer at Harvard and taught classes that were not even listed in the catalog due to her gender.  In 1956, she became a full professor of astronomy at Harvard and then became the first woman department chair there.  I thought it was particularly nice to see that she won the Russell prize of the AAS in 1977.  Both Eddington and Shapley were impressed with her brilliance.  They became the mentors and promoters of her career that helped her have a productive life as a professional astronomer in spite of the biases of the time.