Summary

After having studied this lecture, you should be able to

• Describe the main galaxy types, Es and Ss, and list five characteristics of each
• Describe the main properties of Globular Clusters and of Open Clusters.
• Define surface brightness, and show it to be independent of distance.
• Derive the relation between the surface density of stars in a galaxy, and its surface brightness.
• Derive the relation between the stellar density and star counts
• Know where to find web-pages with images of galaxies.