Overall rotation of a many-body system in Dixon's theory

Using Dixon's theory, an expression for the angular momentum of an N-body system, whose constituent bodies are monopoles that do not interact gravitationally, is obtained. In this expression the contributions to the angular momentum due to the rotational and internal motions of the material system are separated. It is also shown how the existence of a frame with respect to which the total angular momentum of an N-body system is reduced to an expression formally similar to that corresponding to a rigid body instantaneously equivalent to the material system considered. Finally, in space-times of small curvature, a separation of the energy into a part due to the rotational motion and other due to the internal motion, is investigated. (C) 1996 American Institute of Physics.