AST 101 Lecture Notes - Lecture 17: Type Ia Supernova, Large Magellanic Cloud, Inverse-Square Law
Document Summary
About 2/3rd of spirals show a central bar - region where stars orbit in long, We see some spirals on edge on the dust and gas can block the star light. Smooth appearance no obvious internal structure. Can contain in excess of 1 trillion stars. Very little gas very little new star formation. Stars in elliptical are mainly red giants and very low mass main sequence stars, hence red cole. Shape is neither disk like nor smooth and rounded. **large magellanic cloud ionization nebulae show that the galaxy is experiencing ongoing star formation experience encounter. The milky way and andromeda are on collision course and will eventually. Mergers may transform spiral galaxies into elliptical. Hubble settle spiral nebulae debate using this to measure andromeda. Objects for which some fundamental property is known that can be used to measure. Distance can be determined by comparing observed brightness and luminosity. Relationship between apparent brightness and luminosity depends of luminosity by fusion distance.
