AST-1A Chapter Notes - Chapter 16: Dwarf Elliptical Galaxy, Spiral Galaxy, Milky Way
Document Summary
Spiral: such as our own, look like flat white disks with yellowish bulges at the centre with spiral arms. Elliptical: redder, rounder, and often elongated irregular: neither disklike nor rounded. Galaxies come in many different sizes: dwarf galaxies (10^9) to giant galaxies (10^12) stars. Have a disk, a bulge and a halo. Disk stars orbit in the same plane with all ages of stars. Halo stars have random orbits with old and low mass stars. Disk component: follow orderly nearly circular orbits around the center. Halo component: rounded or elliptical shape containing little cool gas and dust that. Can have both halo and disk components in one galaxy. Barred spirals appear to have a straight bar of stars cutting across the center have orbits at different inclinations with spiral arms curing either way the milky way is one. Small dwarf elliptical galaxies are more common. Containing very little dust or cool gas.
