ASTR 1210 Chapter Notes - Chapter 19: Galactic Center, Superbubble, Hydrogen Atom

• School: University of Virginia
• Department: Astronomy
• Course: ASTR 1210
• Professor: Murphy Edward

Document Summary

Flat disk of stars surrounded by a bright central bulge. Disk is surrounded by dimmer, rounder halo. Individual stars bob up and down through the disk as they orbit (like merry go round) General orbit of a star around the galaxy arises from its gravitational attraction toward the galactic center, while the bobbing arises from the localized pull of gravity w/in the disk itself. Each orbit takes 200 million years, each bob up and down takes 10s of millions of years: orbits of halo and bulge stars. Bulge/halo stars travel around the galactic center on more or less elliptical paths, but the orientations of these paths are relatively random. Halo stars: swoop from high above the disk to far below it and back again, plunging through disk at high velocities. Swooping orbit explains why bulge/halo are puffier than disk: stellar orbits and the mass of the galaxy. Sun orbits in the disk and takes 230 million yrs.