Summary

After having studied this lecture, you should be able to

• describe the surface brightness profiles of Es in terms of the de Vaucouleurs profile.
• explain why we think that this profile results from galaxy encounters.
• recall that Es have typically hundreds of GCs.
• explain why dust lanes in Es and shells of stars around Es are thought to be evidence for galactic cannibalism.
• contrast the stellar population and ISM of Es with those of Ss.
• describe how X-rays are detected, and explain the process with which X-rays are produced in the hot gas in Es. (But not be able to recall the equation, or reproduce the calculation.)
• explain how X-ray observations can be used to infer the gravitational potential in Es.