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WonderAstronomy biography fact

In her 1925 doctoral thesis, the British-American astronomer Cecilia Payne showed that stars are made mostly of hydrogen and helium, unlike the Earth. She read this from starlight split into its colours, using new physics that explained how heat strips electrons from atoms.

Cecilia Payne-Gaposchkin

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The story behind the card

At the time, astronomers assumed stars had roughly the same make-up as the Earth. Working at Harvard College Observatory, Payne showed that the differences between star spectra, starlight spread out into its colours, came mainly from temperature rather than composition, and that hydrogen was vastly more abundant than anyone expected. Henry Norris Russell, the leading American astronomer, found this implausible, and in the published thesis she called her own hydrogen figure 'almost certainly not real'. Four years later Russell reached the same result by other means and acknowledged her work. The astronomers Otto Struve and Velta Zebergs later called hers the most brilliant PhD thesis ever written in astronomy. In 1956 she became the first woman promoted to full professor in Harvard's Faculty of Arts and Sciences.

Türkçe oku
İngiliz asıllı Amerikalı astronom Cecilia Payne, 1925'teki doktora tezinde yıldızların Dünya'dan farklı olarak büyük ölçüde hidrojen ve helyumdan oluştuğunu gösterdi. Bu sonuca, renklerine ayrılmış yıldız ışığını, sıcaklığın atomlardan nasıl elektron kopardığını açıklayan yeni fizik bilgisiyle okuyarak ulaştı.

O dönemde astronomlar yıldızların aşağı yukarı Dünya ile aynı maddelerden oluştuğunu düşünüyordu. Harvard Gözlemevi'nde çalışan Payne, yıldız tayfları, yani renklerine ayrılmış yıldız ışığı arasındaki farkların bileşimden değil, esas olarak sıcaklıktan kaynaklandığını ve hidrojenin beklenenden kat kat bol olduğunu gösterdi. Dönemin önde gelen Amerikalı astronomu Henry Norris Russell bu sonucu akla yatkın bulmadı; Payne de yayımlanan tezinde kendi hidrojen oranı için “neredeyse kesinlikle gerçek değil” diye yazdı. Dört yıl sonra Russell başka yollardan aynı sonuca ulaştı ve Payne'in çalışmasını teslim etti. Astronomlar Otto Struve ve Velta Zebergs, onun tezini sonradan astronomide yazılmış en parlak doktora tezi olarak niteledi. Payne, 1956'da Harvard Sanat ve Bilim Fakültesi'nde profesörlüğe yükselen ilk kadın oldu.

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Background reading: Cecilia Payne-Gaposchkin
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