533 rhr then gm r 13 vc r 0876 hr 1 r 23 4182013

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Unformatted text preview: gas as a func8on of radius •  Then use the axis ra8o of the galaxy to get the edge- on velocity (same as for star orbi8ng Galac8c center) •  If gravity were due to only an exponen8al disk, with scale length hR, and r=0.533 R/hR then: GM r 1.3 vc (R) ≈ 0.876 hR 1 + r 2.3 !! 4/18/2013 UW, ASTR 323, SP13, Eric Agol ©2013 5 Spiral rota8on curves 4/18/2013 UW, ASTR 323, SP13, Eric Agol ©2013 6 Spiral Structure •  Winding problem: if spiral pa^ern were due to a set of clouds or stars, spiral pa^ern would rapidly become very _______ wound •  Broadly speaking spiral structure lies between two extremes: –  gra...
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This document was uploaded on 04/05/2014.

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