Evidence in Elliptical Galaxies

Another clue in the formation of globular clusters is that some elliptical galaxies have "bimodal" (two peaks) color distributions of globulars, indicating that there may have been two distinct periods of globular cluster formation in the history of the galaxy. We may surmise that this resulted from collisions between galaxies initiating new star formation. As we shall see in Chapter 24, large elliptical galaxies are thought to be produced by the merger of smaller galaxies.