Proposed in her 1925 doctoral dissertation at Harvard that stars were composed mainly of hydrogen and helium. That was roundly rejected by the scientific establishment of the era.
By the late 1920s, other astronomers supported her theory, overturning the previous dogma.
When she arrived at Harvard, women were not permitted teaching positions. By the 1930s she was teaching informally, her courses were not listed in the Harvard Catalog until 1945. In 1956, she was finally promoted to full professor.
Her hyphenated name, unusual for the era, reflects her marriage to Russian astrophysicist Sergei I. Gaposchkin, whom she met at a conference in Germany. He could not return to the USSR, due to his politics.
Sources:
“Celia Payne-Gaposchkin.” Wikipedia (website). Accessed 28 December 2021