Gravitational drag
Dynamical friction
The gravitational interaction between a relatively massive body and a field of much less massive bodies through which the massive body travels. As a result, the moving body loses momentum and kinetic energy. An example of dynamical friction is the sinking of massive stars to the center of a star cluster, a process called mass segregation. Dynamical friction plays an important role in stellar dynamics. It was first quantified by Chandrasekhar (1943).
Gravitational interaction