Generalization of the Hill problem as an application for the Trojan   asteroids of the solar system
  The restricted four body problem studies the dynamics of a massless particle under the gravitational force produced by three masses (primaries) in an equilateral configuration. One primary, say m3, is considered too small compared with the other ones. In a similar way as in the classical Hill problem, we study the limit case when m3 tends to zero in the Hamiltonian of the R4BP. In this paper we prove that such limit exists and the resulting limit problem produces a new Hamiltonian that inherits some basic features of the restricted three and four body problems. We analyze some dynamical aspects of this new system that can be considered as a generalization of the Hill problem. 
Jaime Burgos-Garcia and Marian Gidea
math.DS