AST201H1 Chapter Notes - Chapter 19.1-19.4: Event Horizon, Density Wave Theory, Subatomic Particle

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Bryan Gaensler

Document Summary

Light of milky way comes from many individual stars. Much of galaxy"s visible light is hidden from our view. Spiral arms are part of flat disk of stars surrounding a bright central bulge. Most prominent stars are found in the 200 globular clusters of stars. Interstellar medium: interstellar gas and dust, hides most of galaxy. Each individual star follows its own orbital path around the center. Nearly the same plane - bob up and down. 1,000 light-year thickness --> barely 1% of 100,000 light-year diameter or disk. Each star"s orbit takes more than 200 million years. Each up/down bob takes tens of millions of years. Orbital velocities of stars near edge and center are about the same. Soar high above and below disk on randomly oriented orbits. Stellar orbits and the mass of the galaxy. Sun/neighbours orbit at about 220 kilometers per second. Takes sun about 230 million years to complete one orbit around galactic center.