In 1925, Cecilia Payne authored what Otto Struve called (in 1962) "undoubtedly the most brilliant Ph.D. thesis ever written in astronomy." Many astronomers agree with Struve's estimation today. Over the next 54 years, until shortly before her death in 1979, Payne-Gaposchkin worked in the fields of stellar spectroscopy and variable star research. As a scientist, she helped lay the foundation for the discipline of astrophysics while paving the way for women to participate in professional astronomy on equal footing with their male colleagues.
Cecilia Payne was born in Wendover, England, on May 20, 1900. Early on she acquired a love for science by pouring through books on botany, chemistry, and physics in her family's home library. In her autobiography, The Dyer's Hand, Payne-Gaposchkin remarked, "I knew, as I had always known, that I wanted to be a scientist . . . [but] was seized with panic at the thought that everything might be found out before I was old enough to begin!"
At the Centenary, Owen Gingerich told the fascinating story of Cecilia Payne's thesis. As a student at Cambridge University studying botany in 1919, Payne heard a lecture at which Arthur Eddington reported that solar eclipse experiments confirmed Einstein's general theory of relativity. Excited, Payne immediately deserted botany for physics. Because sexism prevented women from doing professional research in England at the time, Payne matriculated at Harvard College in 1923 to do her graduate work under Harlow Shapley.
|Atendees of "Starry Universe" gather in front of Philips Auditorium at the Harvard-Smithsonian Center for Astrophysics.|
With a keen interest in stellar spectroscopy, Payne immediately began work that she would build upon to write her Ph.D. thesis, Stellar Atmospheres. In the thesis, Payne combined freshly minted atomic theory with spectroscopic observations to calculate the relative abundance of eighteen chemical elements commonly found in the atmospheres of stars. Payne's thesis established the fact that different stellar spectra result from physical conditions in stars, not from chemical abundance variations. According to Gingerich, "Cecilia Payne-Gaposchkin's result was so ingenious that it turned the problem of stellar temperatures into a non-problem, leading astronomers to forget the importance of her contribution."
The story gets even better, though, as Gingerich told attendees. Payne's calculations suggested that hydrogen and helium are, respectively, a million and a thousand times more abundant in stars than on Earth. Because that result conflicted with prevailing theories of the day, Payne left it out of her thesis. In Through a Universe Darkly, Marcia Bartusiak quotes Jesse Greenstein as saying that Payne "was bullied" into retreating from the discovery. Gingerich himself suggested that Henry Norris Russell persuaded Payne to keep it out. Later during the Centenary, Christopher Sneden said his reading of Payne's thesis is that she had serious doubts about the overabundances based on the data available at the time. But in England shortly after putting her thesis to bed, Payne shared her suspicion about hydrogen with Eddington. In any event, Payne received less than her due credit four years later when Russell convinced the astronomical community that hydrogen, indeed, is the overwhelmingly preponderant element in the universe.
Payne was the very first person at Harvard to receive a Ph.D. in astronomy, essentially creating the university's astronomy department. Unfortunately, gender bias prevented Harvard from elevating Payne to a professorship until 31 year later. During her first decade of professional work, Payne focussed on stellar spectroscopy. Then in 1933 she met Russian astronomer and refugee Sergei Gaposchkin, an eclipsing binary specialist whom she married in March 1934.
At the Centenary, AAVSO Director Janet Mattei said the union led Payne-Gaposchkin to work on the Milton Bureau variable star survey from 1937 to 1952. The survey used Harvard plates for 1898-1947 to make 1,263,562 estimates for 1512 stars, classifying them into eleven categories (compared with the over one hundred categories and sub-categories used by the GCVS today.) In 1950, Payne-Gaposchkin wrote The Galactic Novae, which Janet described as still valuable for cataclysmic novae observers. In the 1970s, as satellites began stretching observations outside the visible range of the electromagnetic spectrum, Payne-Gaposchkin fully appreciated that her childhood fear of science discovering everything before she could begin was adorably immature.
In the course of their presentations, Centenary participants shared fond memories and kind words about Cecilia Payne-Gaposchkin. Gingerich described Mrs. G., as her students eventually called her, as "an imposing presence, formidable in intellect and stature, yet personally kind and gentle." Payne-Gaposchkin's daughter, Katherine Haramundanis, related that her mother's fondness for music was so great that she avoided a career as a conductor for fear that the emotion would control her. Janet Mattei shared how, as a high school student in Turkey, she was impressed by the lucidity of Payne-Gaposchkin's introductory astronomy textbook and the way it punctuated the science with excerpts from poetry. David Latham, who was a student in 1963 in Mrs. G.'s last course on spectroscopy, was so moved by her impeccable delivery and love for the subject that he became a spectroscopist himself. All who had the chance to know Payne-Gaposchkin or just to see her talk said she had a remarkably personal relationship with all the stars she studied, treating each one as a friend.
Attendees not only heard about Cecilia Payne-Gaposchkin but learned some science as well. Of particular interest to AAVSO members, Scott Kenyon talked about symbiotic binary stars. He shared speculation that BG Geminorum's hot star might be a black hole, and that CH Cygni might contain a third star. Wendy Freedman described the Hubble Space Telescope Key Project on the Extragalactic Distance Scale, which is calibrating the period-luminosity relationship in Cepheids in the Large Magellanic Cloud. Freedman said combining the current results from all relevant sources gives a Hubble constant of around 74 km/sec/Mpc. Janet Mattei shared how AAVSO members have been contributing to variable star surveys, satellite observations, and other professional research.
Members interested in reading the Centenary proceedings should look for a volume to be published by L. Davis Press. Meanwhile, the Center for Astrophysics announced that it will host an annual lecture in honor of Cecilia Payne-Gaposchkin beginning in 2001. Director Irwin Shapiro reports that CfA is trying to raise an endowment for these lectures and would be grateful to receive contributions.