Existence of a lower bound for the distance between point masses of relative equilibria for generalised quasi-homogeneous n-body problems and the curved n-body problem

We prove that if for relative equilibrium solutions of a generalisation of quasi-homogeneous n-body problems the masses and rotation are given, then the minimum distance between the point masses of such a relative equilibrium has a universal lower bound that is not equal to zero. We furthermore prove that the set of such relative equilibria is compact and prove related results for n-body problems in spaces of constant Gaussian curvature. (C) 2015 AIP Publishing LLC.