PSEUDOMOMENT STELLAR DYNAMICS .1. SPHEROIDAL GALACTIC EQUILIBRIA

A system of pseudomoment fluid equations is developed and applied to the study of spherically distributed stellar populations. The first equation in the pseudomoment hierarchy is formally analogous to the Jeans equations except for the simplifying absence of a term proportional to a (radially) differentiated pseudomoment dispersion (or inverse ''temperature''). From the next set of equations in the pseduomoment hierarchy a simple relation between stellar nonisothermality and radial anisotropy variation is obtained and shown to yield an increasing radial anisotropy with Galactocentric distance for realistic models. A simple relation is derived between the stellar radial pseudomoment dispersion and the circular speed profile. Using the rotation curve analysis of Salucci and Frenk (1992), an increasing rate of falloff in the stellar number density with radius is predicted, for which some observational support exists (Saha 1985). An additional relation between the density and potential for a mildly flattened tracer population is derived and applied toward an estimate for the asphericity of the Galactic potential and the dark halo. Based on Hawkins's (1984) study of RR Lyrae stars within 60 kpc, a nearly spherical Galactic potential and a mildly flattened dark halo (q(rho) approximate to 0.7) are indicated.