Energy dissipation due to mass loss in a rotating system.

When a rotating magnetized system (angular speed Omega), such as a planet or star, loses mass, there is necessarily an energy dissipation associated with the mass loss. Consider mass loss at rate M, such that the matter is flung off with the orbital speed Omega(R1) at a radius R1 much greater than R0, where R0 is the radius of the planet or star. The power released is approximately equal to the power P(rot) = 1/2M Omega-sq(R-sq) carried off in rotational kinetic energy. Part of the energy released is carried off as magnetic energy in the escaping plasma, and the remainder is released through dissipation of currents. Such dissipation plausibly leads to the acceleration of particles. The power released should be important for Jupiter and for some rapidly rotating stars. For most stellar systems, the power released is small compared to that required to drive a wind.