ABEL MODELS FOR TRIAXIAL SYSTEMS

We present the general theory of equilibrium components of collisionless stellar systems in a Stackel potential, for which the relation between mass density and distribution function can be written as an Abel integral. These Abel-components are generalizations of the well-known spherical models by Eddington and Osipkov-Merritt. Their most important properties include analytical simplicity, which is convenient, and the freedom of an arbitrary function in their definition, which makes it conceivable to combine them in order to model galaxies more realistically. We further show that the Abel-components can be divided into three classes with different dynamical properties, and we discuss their orbital contents.