Document Type

Other

Publication Date

2026

Abstract

How bright a star appears to an observer on earth and what color or colors make up its light can tell a lot about a star. The brightness offers a clue to how far away a star is. The color indicates how hot the star is. Together they may suggest the size of a star. Examining the details of the star light with a spectroscope shows the various colors that come from the star and indicates the very specific colors that are muted or missing, as well as those that are brighter than expected (absorption and emission spectra). This gives additional clues to the temperature of the star and what elements are present in the star. Sometimes these patterns of muted (or brighter) color lines shift or even oscillate about a central color. The shifting may mean an overall motion of the star (red shift or blue shift – special cases of the Doppler shift) while the oscillations suggest a companion star orbiting with the visible one (spectroscopic binary). Consider these muted/missing colors (or brighter colors) like fingerprints of elements on earth. They usually appear as lines because of the way the spectroscope records the colors.  Also, how narrow or broad the lines appear provides evidence of the pressure the elements are under, which are in the outer layers of the star (i.e. pressure broadening). So even though this star is incredibly far away, it’s possible to understand its size, composition, and temperature from the color and brightness.

Publisher

South Dakota State University

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