Woman who found hydrogen in the stars

Cecilia Payne, born on May 10, 1900, in Wendover, England, began her scientific career in 1919 with a scholarship to Cambridge University, where she studied physics. But in 1923 she received a fellowship to move to the United States and study astronomy at Harvard. Her 1925 thesis, Stellar Atmospheres, was described at the time by renowned Russian-American astronomer Otto Struve as “the most brilliant PhD thesis ever written in astronomy”.

In the January, 2015, Richard Williams of the American Physical Society, wrote: “By calculating the abundance of chemical elements from stellar spectra, her work began a revolution in astrophysics.”

In 1925 Payne received the first PhD in astronomy from Radcliffe, Harvard’s college for women,  – because Harvard itself did not grant doctoral degrees to women.

In the early 1930s she met Sergey Gaposchkin, a Russian astronomer who could not return to the Soviet Union because of his politics. Payne was able to find a position at Harvard for him. They married in 1934.

Finally, in 1956, she achieved two Harvard firsts: she became its first female professor, and the first woman to become department chair.

In a 2016 article about Payne for New York magazine, writer Dava Sobel reports that when she arrived at Harvard, Payne found the school had a collection of several hundred thousand glass photographs of the night sky, taken over a period of 40 years. Many of these images stretched starlight into strips, or spectra, marked by naturally occurring lines that revealed the constituent elements.

As she painstakingly examined these plates, Payne reached her controversial – and groundbreaking – conclusion: that unlike on Earth, hydrogen and helium are the dominant elements of the stars.

At the time, most scientists believed that because stars contained familiar elements such as silicon, aluminium and iron, similar to Earth’s make-up, they would be present in the same proportions, with only small amounts of hydrogen.

Although the presence of hydrogen in stars had been known since the 1860s, when chemical analysis at a distance first became possible, no one expected the great abundance claimed by Payne.

Richard Williams, writing for the American Physical Society in 2015, said: “The giants – Copernicus, Newton, and Einstein – each in his turn, brought a new view of the universe. Payne’s discovery of the cosmic abundance of the elements did no less.”

However, at the time of her thesis publication the foremost authority on stellar composition, Henry Norris Russell, of Princeton University, convinced Payne that her conclusions had to be wrong, encouraging her write that her percentages of hydrogen and helium were “improbably high” and therefore “almost certainly not real”.

But in brilliant vindication, Russell devoted the next four years to studying Payne’s findings, and in the July 1929 issue of the Astrophysical Journal, he agreed with her and cited her 1925 study, concluding for the record that the great abundance of hydrogen “can hardly be doubted”.

Cecilia Payne-Gaposchkin died on December 7, 1979.

Please login to favourite this article.