The Composition of Stars The compositions of stars are determined through spectroscopy . Spectroscopy is the study of something using spectra. Recall from the Electromagnetic Radiation chapter that a spectrum is what results when you spread starlight out into its individual colors. By noting what absorption lines (or sometimes, emission lines ) are present and their strengths, you can find out a tremendous amount of information. Stars have absorption lines patterns similar to the Sun. This means that they are composed mostly of hydrogen and helium with traces of other elements. From these absorption lines you learn some important things besides the star's composition: 1. Structure of stars: From the simple fact that you see absorption lines in most stellar spectra, you know that the stars must have a hot dense part that produces a continuous spectrum and an outer layer, or atmosphere, made of cooler, low density gas. The general trend is density and temperature of stars decreases as the distance from the star's center
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.