“There is no joy more intense than that of coming upon a fact that cannot be understood in terms of currently accepted ideas."
Astronomer Cecilia Payne-Gaposchkin was born #OTD in 1900. She used quantum mechanics to decode the spectral lines of stars and deduce their elemental composition, concluding they are mostly H and He, and was the first woman to be made full professor and department chair at Harvard.
Image: Harvard Observatory
Cecilia Payne was born in England, the daughter of a lawyer and a painter who held the radical view that girls should get the same quality education as boys. She excelled in school, and eventually enrolled at Cambridge.
She began visiting the Cambridge Observatory, and asked the staff so many questions that they fetched Eddington to deal with her. He recommended some books for her to read, but she had already read them all. So he just gave her the run of the observatory's research library.
Cambridge wasn’t awarding degrees to women yet, so in 1923 Cecilia moved to the US. Harlow Shapley, director of the Harvard College Observatory, offered her a graduate fellowship.
Shapley believed that the Milky Way was the whole universe. In 1924 he received a letter from Edwin Hubble showing that the Andromeda nebula was a separate galaxy. Payne was in Shapley’s office at the time, and he said to her "Here is the letter that has destroyed my universe."
More here: https://mastodon.social/@mcnees/109614690601381175
In her thesis, Payne applied developments in quantum mechanics to understand the observatory's immense catalog of stellar spectra. She estimated elemental abundances in stars and showed that spectra were influenced by the amount of ionization at different temperatures.
Payne's thesis "Stellar Atmospheres" was published in 1925. The astronomers Otto Struve and Velta Zeberg supposedly said it was "undoubtedly the most brilliant Ph.D. thesis ever written in astronomy."
https://ui.adsabs.harvard.edu/abs/1925PhDT.........1P/abstract
Before Payne's work, the accepted theory significantly underestimated the abundance of Hydrogen and Helium in stars. Existing models assumed the composition of the sun was similar to that of Earth.
Estimates of the amount of H were made using Balmer absorption. But this involves H atoms in the first excited state. Payne realized that for the 5800K surface temp of the sun, only 1 per 10⁸ H atoms are in this state.
She concluded that stars are mostly H and He!
[Enter villain]
Henry Norris Russell, a prominent astronomer, was *sure* Payne was wrong. He convinced her to omit the result from her thesis.
A few years later he realized that HE was wrong, and published the result himself.
https://ui.adsabs.harvard.edu/abs/1929ApJ....70...11R/abstract
The energy of binding of an electron in different quantum states by neutral and singly ionized atoms is discussed with the aid of tables of the data at present available. The structure of the spectra is next considered, and tables of the ionization potentials and the most persistent lines are given. The presence and abseice of the lines of different elements in the solar spectrum are then simply explained. The excitation potential, E, for the strongest lines in the observable part of the spectrum is the main factor. Almost all the elements for which this is small show in the sun. There are very few solar lines for which E exceeds 5 volts; the oniy strong ones are those of hydrogen. The abundance of the various elements in the solar atmosphere is calculated with the aid of the calibration of Rowland `s scale developed last year and of Unsold's studies of certain important lines. The numbers of atoms in the more important energy states for each element are thus determined and found to decrease with increasing excitation, but a little more slowly than demanded by thermodynamic considerations. The level of ionizatioii in the solar atmosphere is such that atoms of ionization poten- ~ hal 8.3 volts are 50 per cent ionized. Tables are given of the relative abundance of fifty-six elements and six compounds. These show that six of the metallic elements, Na, Mg, Si, K, Ca, and Fe, contribute 95 per cent of the whole mass. The whole number of metallic atoms above a square centi- meter of the surface is 8 X ic20. Eighty per cent of these are ionized. Their mean atomic weight is 32 and their total mass 42 mg/cm2. The well-known difference between ele- ments of even and odd atomic number is conspicuous-the former averaging ten times as abundant as the latter. The heavy metals, from Ba onward, are but little less abundant than those which follow Sr, and the hypothesis that the heaviest atoms~ sink below the photospifere is not confirmed. Tue metals from Na to Zn, inclusive, are far more common than the rest. The compounds are present in but small amounts, cyanogen being rarer than scandium. Most of those elements which do not appear in the solar spectrum should not show observable lines unless their abundance is much greater than is at all probable. There is a chance of finding faint lines of some additional rare earths and heavy metals, and perhaps of boron and phosphorus. The abundance of the non-metals, and especially of hydrogen, is difficult to estimate from the few lines which are available. Oxygen appears to be about as abundant by weight as all the metals together. The abundance of hydrogen may be found with the aid of Menzel's observations of the flash spectrum. It is finally estimated that the solar atmosphere contains 6o parts of hydrogen (by volume), 2 of hdium, 2 of oxygen, i of metallic vapors, and o.8 of free electrons, practically all of which come from ionization of the metals. This great abundance of hydrogen helps to explain a number of previously puzzling astrophysical facts. The temperature of the reversing layer is finally estimated at 5600° and the pressure at its base as 0.005 atm. A letter from Professor Eddington suggesting that the departure from the thermo- dynamic equilibrium noticed by Adams and the writer is due to a deficiency of the num- ber of atoms in the higher excited states is quoted and discussed
I’ve seen claims that Henry Norris Russell cited Payne on this result, but reading through his paper my impression is that he did not give Payne nearly as much credit as she deserved for the Hydrogen and Helium abundances.
He cites Payne when discussing heavier elements, but when he arrives at the surprising result on the abundance of Hydrogen – a major discovery – he fails to mention that he convinced Payne to leave it out of her thesis. Maybe I'm missing something or he gave credit elsewhere.
Payne's work revolutionized our understanding of the composition of the universe.
Almost everything out there is hydrogen and helium. The heavier elements we see here on Earth are just a tiny fraction of the total.
From the time she finished her PhD until 1938, Payne's title was "technical assistant" to Harlow Shapley. She performed all the duties of a Harvard professor, but women were not officially promoted to that position. In 1938 she was given the title "Astronomer."
Finally, in 1956 she became the first woman promoted to Full Professor at Harvard. That same year she became the first woman to head a department at Harvard, when she was appointed Chair of Astronomy.
Now, this is neither here nor there, but around 1976, Cecelia and a friend made this absolutely rad needlepoint of the Cassiopeia A supernova remnant.
Images and other materials: https://hollisarchives.lib.harvard.edu/repositories/4/archival_objects/1021816
@mcnees offtopic: that would make a cool boss on a 8-bit game. 
(sorry couldn’t resist 
)
@mcnees When I saw this T-shirt I made an eeping sound and bought it.
Guess she never had a dog.
Looks like a member of #Kraftwerk.
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