Q Part 1: The work performed by Payne-Gaposchkin introduced the idea that all stars have the same "recipe" of 99% Hydrogen & Helium with all other elements in tiny quantities. Explain why her contemporaries found this idea to be extremely unlikely. Then, discuss how it is possible that absorption lines from other elements, such as Carbon, Iron, Sodium, etc are easily measured in M-stars despite being less than 1% of their overall composition. Part 2: The colors of "blue" & "red" stars are not quite the color expected by their namesake when you actually look at them. Explain why a "blue" star appears "bluish white" rather than the blue in the Facebook logo. Finally, briefly describe the physical property that separates 3 groups on the H-R diagram (note: it is not the size or temperature).