Expanding,homogeneous, ellipsoidal density perturbations. III. A simple theory for the acquisition of angular momentum by tidal torques with the effects of the spin growth on the expansion included

The effects of the acquisition of angular momentum on the expansion of homogeneous, ellipsoidal density perturbations is investigated by generalizing the theory of previous papers of this series, where spin grows to the first order in overdensity. A small difference is found to be between the two cases, except for the fact that the body under consideration becomes unbound earlier in the current approach. A comparison is also made with the results of a different theory, where spin grows to the second order in overdensity. Quasi-oblate triaxial configurations turn out to gain less angular momentum in respect to both oblate and more elongated configurations with same minor to major axis ratio. In all cases of physical interest, the spin growth from the beginning to the maximum ellipsoidal volume exceeds the spin growth from the maximum ellipsoidal volume to the turnaround of the major axis, by a factor of at least 3. It is also inferred that the spin growth from the turnaround of the major axis on, probably does not exceed about one third the angular momentum previously gained.