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The Most brilliant PhD thesis ever written in astronomy was stolen!

Updated: Aug 3


Dear young scientist,

My name is Juna Asfuroglu, and in today's blog, I will be restoring justice to Cecilia Payne-Gaposchkin who during the year 1925 produced a thesis that the sun was composed mostly of hydrogen and helium. Sadly, like many women back then her thesis statement was called “impossible”. Years later the man who rejected her work realized that she was right, took all the credit for her work, and claimed that he researched the topic for decades. We scientists must bring justice to those who had been wronged a long time back, and it's a scientist's right to take credit for their discoveries. 


Cecilia Payne-Gaposchkin was a British-born American astronomer who discovered that stars are made mainly composed of hydrogen and helium and stated that stars could be classified according to their temperatures. She broke through barriers and proved previous scientists wrong that the Sun and Earth are not made out of the same material, thus having different independent celestial compositions. 


Her discoveries and statements had revolutionized the history of astronomy. For example in one of her books “The Stars of high luminosity,” she stated how unrepresentative spectroscopic material is, partly because spectra even of giant stars are available only to a distance of about one kiloparsec and partly because a considerable number of high luminosity stars of early type, such as Alcyone, are spectroscopically unrecognizable. 


Cecilia Payne-Gaposchkin

Stars that are brighter than their apparent magnitude, are unusually massive and have a very low density of exceptionally high energy output (per unit mass), and this is a very untypical occurrence of events. The infrequency Of the supergiant in space has an important bearing on its age and history, arguing for unlikely.

 

Moreover, most spectroscopically and photometrically recognizable supergiants seem to be isolated stars, however, some are members of clusters. For example, the Supergiants in galactic clusters are preponderantly B stars, End in globular clusters, invariably red stores. Also, there isn't much systemic systematic difference in brightness or spectrum between cluster super giants and isolated supergiants. 




This then led to the conclusion that stars generally are composed of the same elements, but their size has a huge impact on the energy they produce, and even their color and the way their life ends differ as well, For example super giants explode into a supernova, and can take a form as black holes or neutron stars. 



What led to her making such an impactful discovery? She decoded the complicated spectra of starlight to learn the different amounts of chemical elements in stars. One of the observations that Gustav Kirchoff and Robert Bunsen made was that the spectra of light given off by the incandescent gas contains different elements and each element has its own characteristic set of spiral lines, which later became a unique mark for identification. When William Huggins observed many of these lines in the spectra of stars. Turns out the visible universe had similar elements present on Earth. 


Payne started measuring the absorption lines in stellar spectra, after a few years she showed a wide variation in stellar spectra, and it is because of different ionization states of the atom that caused different surface temperatures of stars, not because of different amounts of elements. When she compared the elements of each star she realized they were mainly composed of the 2 lightest elements, they are Hydrogen and helium. However, the heavier elements were seen to make less than 2% of the mass of stars. 


This discovery revolutionized the way we perceive the elements in the spiral lines, and provides evidence that planets and stars are composed of different elements. Moreover, at the end of her thesis, she was given a title as a technical assistant only to Professor Shapely; this is because women back then weren't much credited for their work,  and she was never elected to the elite National Academy of Sciences. However, she became a role model to many women in science and her story continues to live on, and a lesson to never give up on your passion even though there are many obstacles blocking that path, like how she conquered that by working twice as much as men to be seen in the scientific community. 



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