AST201H1 Chapter Notes - Chapter 19: Cosmic Dust, Supernova Remnant, Spiral Galaxy
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AST201H1 Full Course Notes
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The mw galaxy has > 100b stars. Spiral galaxy: galaxies that look like flat white disks with yellowish bulges at their centers: the disks are filled with cool gas and dust, interspersed with hotter ionized gas. Spiral arms: the bright, prominent arms, usually in a spiral pattern, found in most spiral galaxies. Disk: the portion of a spiral galaxy that looks like a disk and contains an interstellar medium with cool gas and dust: most of the galaxy"s bright stars reside here. Bulge: the central portion of a spiral galaxy that is roughly spherical (or like a football) and bulges above/below the plane of the galactic disk. Halo: spherical region surrounding the disk of a spiral galaxy: dimmer and rounder than the disk. Globular cluster: a spherically shaped cluster of 1m+ stars: found primarily in the halos of galaxies and contain only very old stars.