Chp17 - SCCC 115 Homework 8 - Due 9 Nov. 2003 Prof....

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SCCC 115 Homework 8 - Due 9 Nov. 2003 Prof. Christina Lacey R&D: 17-7, 17-8, 17-10, 17-14, 17-16 P: 17-3, 17-4, 17-10 What is the difference between absolute and apparent brightness? The absolute brightness of a star is an intrinsic property and directly proportional to the luminosity. The absolute magnitude is the brightness of a star at 10 pc. Apparent brightness is the brightness measured by observers at Earth and depends explicitly on the 1/distance . If the distance is known than the absolute brightness can be calculated from the apparent brightness. How do astronomers measure stellar temperatures? The temperature is measured by at least two points, fitted to the black body spectrum. The peak of the spectrum, corresponds to the stellar temperature. Most commonly the points the spectrum are from the B and V (blue and visible (yellow-green) filters. . Why do some stars have very few hydrogen lines in their spectra? Either the staqr is too hot or it is too cold. If the star is too hot, then the hydrogen is ionized
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Chp17 - SCCC 115 Homework 8 - Due 9 Nov. 2003 Prof....

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