AST 2002 Lecture Notes - Lecture 16: Cosmic Distance Ladder, Photon, Hubble Deep Field
Document Summary
Our deepest images of the universe show a great variety of galaxies, some of them billions of light years away. What are the three major types of galaxies. Elliptical galaxy: all spheroidal component, virtually no disk component. Deep observations show us very distant galaxies as they were much earlier in tie (old light from young galaxies) Matter originally filled all pf space almost uniformly. Gravity of denser regions pulled in surrounding matter. Halo stars form first, then everything settles into a disk. Stars continuously form in the disk as the galaxy grows older. The density: elliptical galaxies could come from dense clouds that were able to cool and form before settling into a disk. Collision were much more likely early in time, because galaxies were closer together. Many of the galaxies we see at great distance (and early times) Two can collide and make an elliptical galaxy.
