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Unformatted text preview: Text Quote Notes - Ch. 13 - The Measure of Stars Stars: Distance the first step is measuring distance, brightness, and lumi- nosity of stars distances to nearby stars are measured using parallax d ( pc ) = 1 p 00 (1) 1pc (parsec) = distance of a star with parallax p = 1 00 ( 3.26ly) closest star has p=0.75 00 stars are few and far between in our neighborhood Stars: Luminosity once distance and brightness are known, we can determine a stars luminosity luminosity = 4 d 2 brightness some ? s are 10 10 more luminous than others luminosity range of normal stars is from 10- 4 L to 10 6 L many more low luminosity ? s than high luminosity ones 1 Stars and Radiation: radiation tells us T, L, R measuring the color of a ? tells us its surface temperature (Wien) many more cool ? s than hot ones many more faint ? s than luminous ones compare: 2 ? s with same T, different L; which is larger?...
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- Fall '06