Annu. Rev. Astron. Astrophys. 1991. 29: 239-274 Copyright © 1991 by Annual Reviews. All rights reserved

2.3.3 MAXIMUM STREAMING MODELS There is a special set of self-consistent separable models in which the full variety of box orbits is occupied, but only the thin tube orbits, i.e., those without any radial epicyclic motion, are populated. Their distribution functions can be found explicitly for separable models of arbitrary shapes and density profiles (50, 87, 88, 108, 164, 165, 166, 167, 168, 326). These models are hardly realistic, but they are useful because they allow the explicit calculation of the maximum possible stellar streaming velocities - and hence the maximum possible angular momenta around the long- and the short axis - for any separable triaxial model. This is important for the interpretation of the observed velocity fields of elliptical galaxies, as it puts limits on the amount of streaming for a given triaxial shape.