ASTR-1010 Lecture 19: ASTR 1010 Lecture 19: Lecture 19: The Milky Way
21 Mar 2017
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19. 1: the milky way revealed: dusty gas clouds obscure our view because they absorb visible light, this is the interstellar medium that makes new star systems. Regions of the milky way galaxy: diameter of disk= 100,000 l. y. (30,000 pc, radius of disk = 50,000 l. y. (15,000 pc, thickness of disk = 1,000 l. y. (300 pc, number of stars= 200 billion. Regions of the milky way galaxy: disk, younger generation of stars, contains gas and dust, location of the open clusters, bulge, halo. 3mixture of both young and old stars: older generation of stars, contains no gas or dust, location of the globular clusters. The interstellar medium (ism: the (cid:862)stuff(cid:863) between the stars, mostly a vacuum (atom/cm3, composed of 90% gas and 10% dust, gas: individual atoms and molecules, dust: large grains made of heavier elements.
