astro - unit 7 - sample question answers

# astro - unit 7 - sample question answers - 1 1a stars...

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1 1a stars become variable stars after red-giant stage. Most variable stars represent post-giant stages After the red giant stage a star approaches the white dwarf stage. During this time it may undergo a period of Instability (nova, supernova). The periods of variation in light output of certain classes of these stars are known to be related to their absolute magnitudes. (variable starts) 1b regular variable = A variable star has a predictable period of brightening and dimming. irregular variable = A variable star has an unpredictable period of brightening and dimming. 1c Cepheid I and II variable stars are used as distance indicators 1d another name for Cepheid II stars = W Virginis Cepheids Another name for Cepheid I stars is = classical cepheids 2 C = Cepheid I variables D = Cepheid II variables B = RR Lyrae variables B = shows the period luminosity behavior for Cepheids 3 galactic center = The reference direction for the galactic system galactic latitude is measured perpendicular to the plane of the Milky Way

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2 The galactic coordinate measured in the plane of the Milky Way is galactic longitude galactic system = uses the mean plane of the Milky Way as the reference plane and the direction to the center of the Milky Way as a reference direction. 4a the Sun moves on a nearly circular orbit about the galactic center. The Sun's motion in the galaxy is roughly on a circle centered at the galactic center. . 4b
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## This note was uploaded on 11/08/2011 for the course BIOL 243 taught by Professor Datt during the Spring '08 term at South Carolina.

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astro - unit 7 - sample question answers - 1 1a stars...

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