Density Waves

This animation illustrates how a molecular cloud overtaking a more slowly moving spiral density wave can trigger star formation in the cloud. The molecular clouds passing through the density wave are subjected to compression because it is a region of (somewhat) higher density. This triggers the formation of clusters of new stars, which continue to move through the density wave. The short-lived stars die, most likely as supernovae, before they can leave the spiral density wave. But the longer-lived stars that are formed pass through the slower density wave and eventually emerge on its front side and continue on their way as a slowly dissipating cluster of stars Usage: Click "Play" to begin and "Stop" to halt. "Step" moves forward one step and "Back" moves backwards one step. "Home" returns to the beginning from any point.