恒星动力学是天文物理的一个分支，以统计学的方法介绍恒星在它们共同重力下的集体运动。但重力的长距离效应和恒星系统缓慢的弛豫，阻碍了统计物理方法的使用。一颗恒星在星系或球状星团内的运动，主要受到其它恒星的平均分布和恒星距离的影响，和最邻近的恒星少量的影响。

如果物质的分布是理想化的平滑，恒星的弛豫过程是倾向于每颗恒星有着各别的运动轨迹的。2-体弛豫被限制在一颗恒星和另一颗恒星之间的交互作用下，而"剧变弛豫"是大型恒星集**统集体变异所造成的。

Stellar dynamics is the branch of astrophysics which describes in a statistical way the collective motions of stars subject to their mutual gravity. The essential difference from celestial mechanics is that each star contributes more or less equally to the total gravitational field, whereas in celestial mechanics the pull of a massive body dominates any satellite orbits. Stellar dynamics is usually concerned with the more global, statistical properties of several orbits rather than with the specific data on the positions and velocities of individual orbits. The motion of stars in a galaxy or in a globular cluster are principally determined by the average distribution of the other, distant stars, and little influenced by the nearest stars.