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Unformatted text preview: Chapter 11 Surveying the Stars 327 summary of key concepts 11.1 Properties of Stars How do we measure stellar luminosities? The apparent brightness of a star in our sky depends on both its luminosity the total amount of light it emits into spaceand its distance from Earth, as expressed by the inverse square law for light . We can therefore calculate a stars luminosity from its ap- parent brightness and its distance, which we can measure through stellar parallax. How do we measure stellar temperatures? We measure a stars surface tempera- ture from its color or spectrum, and we classify stars according to the sequence of spectral types OBAFGKM, which runs from hottest to coolest. Cool, red stars of spectral type M are much more common than hot, blue stars of spectral type O. How do we measure stellar masses? We can measure the masses of stars in binary star systems using Newtons version of Keplers third law if we know the orbital period and separation of the two stars.orbital period and separation of the two stars....
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This note was uploaded on 08/16/2011 for the course AST 2002 taught by Professor Britt during the Spring '08 term at University of Central Florida.
- Spring '08