3. Cecelia Payne-Gaposchkin was the physicist who was able to put everything together, showing that the spectra of stars depended on the and the in their atmospheres. She showed that stars were mainly with the next most abundant element being .

Showing that the spectra of stars depended on the ___temperature and the degree of ionization of elements in their atmospheres.

She showed that stars were mainly   hydrogen with the next most abundant element being  helium .

Explanation:

Cecilia Payne worked at the Harvard College Observatory (HCO) where she analyzed for months the spectra of hundreds of stars; she aimed to calculate the elements present in them; and from her observations and studies over the years she discovered the information quoted above.

the historians cited in the article all agree with one another about the cause of the civil war. despite coming from different backgrounds and cultures, the historians agree that slavery was the root cause of the civil war. the fact that all these historiansgenerally agree with one another makes their shared viewpoints more reliable and valid, especially because the historians have different backgrounds and all work for the well-respected institutions of howard university, clemson university, and the university of colorado.

a is the final ! : )