The story of Cecilia Payne-Gaposchkin is a tale of achievement against the odds. Blessed with a brilliant mind, but cursed – professionally - with a womb, she battled endemic prejudice in her chosen field until late in her career. And yet, some of her theories and discoveries rank among the most important in 20th century astronomy.
Cecilia was born in England in 1900. Her father died when she was four, and although she displayed great intellect from an early age, the family’s money was diverted into her brothers’ education. Nevertheless, she won a scholarship to read sciences at Newnham College, Cambridge. It was there, in 1919, that she heard a lecture from Arthur Eddington about using stars to test the Theory of Relativity, and her interest in astronomy was ignited.
She was elected to the Royal Astronomical Society while still a student, but on completion of her studies was denied a degree. At this time, Cambridge did not award degrees to women, and would not until 1948. Realising that her choice of career was impossible in England, she began to look for opportunities in the United States. In 1923 she met Harlow Shapley, the Director of the Harvard College Observatory, who ran a graduate program in astronomy which offered rare fellowships to women. She accepted the offer to further her studies at the Observatory, and there she joined Adelaide Ames, a remarkable young astronomer famed for her pioneering investigations (with Shapley) of spiral nebulae. She and Cecilia were close friends until Adelaide’s tragic drowning in 1932.
Harlow Shapley greatly encouraged Cecilia, and in 1925 she completed a doctoral thesis on “Stellar Atmospheres: A Contribution to the Observational Study of High Temperature in the Reversing Layers of Stars”. Cecilia’s dissertation, the first to earn a Ph.D. in astronomy from Radcliff, was later cited by the great Otto Struve as “undoubtedly the most brilliant Ph.D. thesis ever written in astronomy.”
In basic terms, what the paper showed was that variation in stellar absorption lines is caused by changes in the amount of ionization at different temperatures, and not, as was commonly thought, by differing amounts of elements. Cecilia concluded that elements such as silicon, carbon, and some common metals which are detected in the Sun’s spectral lines are all present in the same relative amounts as on Earth, but that helium and hydrogen are far more abundant. In the case of hydrogen, the ratio is something like a million to one, making it the major constituent of stars and thus the building block of the entire universe.
This significant discovery should have brought Cecilia Payne fame and fortune, but sadly, she went unrewarded. Henry Norris Russell convinced her that the central conclusion of her thesis was unreliable, although some four years later, that noted astronomer used a different method to derive the same results. Russell was always generous enough to acknowledge Cecilia’s work in his papers, but not generous enough to deny himself most of the credit.
For many years, Cecilia worked for pitifully low wages at Harvard, and until 1938 she served as a technical assistant to Harlow Shapley, with no official title. During this time, she surveyed hundreds of thousands of bright stars, including all stars brighter than the tenth magnitude, in order to better understand the structure of the Milky Way galaxy. She also took a trip to Europe in 1933, where she met Sergei Gaposchkin, a Russian-born astrophysicist. She organized a US visa for him, and they married the following year. Over the next few years, Cecilia gave birth to two sons and a daughter, and continued to study the stars.
With husband Sergei and a few other assistants, she conducted more than 1,250,000 observations of variable stars in the Milky Way, and then added a further two million observations from the Magellanic Clouds. The analysis conducted by Cecelia and Sergei laid the foundation for all subsequent study of variable stars, and helped determine the sequential changes of stellar evolution.
In the midst of all this, Shapley campaigned to gain Cecilia a higher standing at Harvard – she was disenchanted and might have left – and in 1938 she was given the title of “Astronomer”. None of the courses she taught were officially recorded until 1945, however. Finally, in 1956, she was promoted to full professor and a little later was granted the Chair of the Department of Astronomy at Harvard, becoming the first woman to head up a department at that august institution.
Cecilia Payne-Gaposchkin died in 1979. Her many accolades include having an asteroid named after her in 1974, and - ironically - the Henry Norris Russell Lectureship for excellence in astronomical research, awarded by the American Astronomical Society in 1976. In the year 2000, a series of lectures on astrophysics was established in her honor by Harvard University.
There have been many notable female astronomers in the past 150 years, from trailblazers like Williamina Fleming and Annie Jump Cannon, to modern giants like Vera Rubin. But it is Cicelia Payne-Gaposchkin who did more than anyone to break down the gender barriers in the field of astronomy, with discoveries that rank among the most important of all time. Of all the remarkable women to have studied the stars, it is Cecilia’s personal star that shines the brightest.