This live script demonstrates a simulation of a spiral galaxy in MATLAB using density wave theory. The density wave theory suggests that the spiral arms of a galaxy are not static, but rather stars move in and out of it based on their own elliptical orbits around the galaxy, such that the arms are a wave of density flowing through the disc. It gives the galaxy its characteristic appearance where the stars rotate in orbit but the shape maintains in place.
--reduced gif file size
--added hyperlinks to web sources