: Explaining the origin and stability of spiral structures through density wave theory.
: Studying processes like dynamical friction (the "drag" on massive objects moving through a sea of stars) and violent relaxation . Essential Resources Galactic Dynamics
: Understanding systems where individual stellar encounters are rare enough to be ignored. This uses the Collisionless Boltzmann Equation and Jeans Equations to describe equilibrium. : Explaining the origin and stability of spiral