NATS 1740 Chapter Notes - Chapter 15: Dwarf Elliptical Galaxy, Inverse-Square Law, Elliptical Galaxy

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Randy Hoffman

Document Summary

Chapter 15 galaxies and the foundation of modern cosmology. Spiral galaxies: like the milky way, look like flat, white disks with yellowish blues at their centres. The disks are filled with cool gas and dust interspersed with hotter ionized gas and usually display spiral arms. Elliptical galaxies: redder, rounder and often longer in one direction that then other like a football. Compared with spiral galaxies, elliptical galaxies contain very little cool gas and dust thought they contain very hot ionized gas. Irregular galaxies: appear neither disklike nor rounded. Spiral galaxies have a disk, bulge and halo just like the milky way. Disk component (population i): flat disk in which stars follow orderly and nearly circular orbits around the galactic centre. Always contains an interstellar medium of gas and dust but the amount may differ from one spiral galaxy to the next. Spheroidal component (population ii): contains little cool gas and dust and stars have orbits with many different inclination s.