Galaxy Collisions

This animation illustrates very schematically one possible mechanism by which one galaxy interacting with another can cause gas to be channeled to the center of a galaxy. This mechanism causes angular momentum to be lost by orbiting hydrogen clouds, which then spiral to the center. This can increase the density in the center and provoke a wave of star formation (starburst), or can feed a black hole at the center, producing an active galactic nucleus. However, the details are not well understood, so the mechanism presented here should be viewed as a plausible possibility at this point. Usage: Click "Play" to begin. Continue to click "Play" when the action stops. "Step" moves forward one frame and "Back" moves backwards one frame. Click "Stop" to pause. "Home" returns to the beginning from any point.