Cecilia Payne-Gaposchkin

Cecilia Payne showed in her 1925 doctoral thesis that stars are made overwhelmingly of hydrogen and helium. The leading astronomer Henry Norris Russell persuaded her to call the result probably not real; he reached the same conclusion by other means in 1929 and was often credited. She stayed at Harvard on low pay for decades before becoming its first woman full professor in 1956.