AST201H1 Chapter Notes - Chapter 20.1-20.3 : Galactic Center, Observable Universe, Elliptical Galaxy

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

Document Summary

When we look at stars that are farther away, we see them as they were in the past. Flat white disks with yellowish bulges at their centers. Disks are filled with cool gas and dust, interspersed with hotter ionized gas. All ages and masses that orbit in the disk of the galaxy. Flat disk in which stars follow orderly, nearly circular orbits around the galactic center. Contains an interstellar medium of gas and dust. Amounts and proportions of molecular, atomic, and ionized gases differ from one to next. Barred spiral galaxies - straight bar of stars cutting across the center, with spiral arms curling away from the ends of the bar. Less cool gas than normal spirals, but more than ellipticals. Usually contain very little dust or cool gas. Some have relatively small and cold gaseous disks rotating at centers. Some contain substantial amounts of very hot gas. Lack of cool gas = little or no ongoing star formation.