Density Waves and the Stability of Galactic Spiral Arms
Density wave theory or the Lin-Shu density wave theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain the spiral arm structure of spiral galaxies. Its primary competitor is the self-propagating star-formation model. The Lin-Shu theory introduces the idea of long-lived quasistatic density waves, which are sections of the galactic disk that have greater mass density. The theory has also been successfully applied to Saturn's rings.