S. Filippi et al., ON THE IMPLICATIONS OF THE NTH-ORDER VIRIAL EQUATIONS FOR HETEROGENEOUS AND CONCENTRIC JACOBI, DEDEKIND, AND RIEMANN ELLIPSOIDS, The Astrophysical journal, 460(2), 1996, pp. 762-776
The implications of the nth-order virial equations are analyzed for co
ncentric heterogeneous ellipsoids with a density distribution of the f
orm rho = rho(c) f(m(2)), where m(2) = Sigma(1=1)(3), x(i)(2)/a(i)(2),
0 less than or equal to m(2) less than or equal to 1, and a(i) are th
e semiaxes of the external ellipsoid corresponding to m(2) = 1. Soluti
ons analogous to Jacobi ellipsoids (with constant angular velocity Ome
ga, without vorticity), to Dedekind ellipsoids (with nonuniform vortic
ity Z and zero angular velocity), and to Riemann ellipsoids (with cons
tant angular velocity and nonuniform vorticity) are explored. It is sh
own that only the second- and fourth-order virial equations give nontr
ivial results: all the odd-order virial equations are identically sati
sfied for ellipsoids rotating around a principal axis of symmetry. The
even-order virial equations (sixth, eighth, etc.) are shown to be a c
onsequence of the lowest order equations. The entire family of homogen
eous and heterogeneous concentric ellipsoids allowed by the virial equ
ations is presented, confronted, and contrasted with the known cases i
n the literature.