EFFECT OF OBLATENESS ON THE NONLINEAR STABILITY OF L-4 IN THE RESTRICTED 3-BODY PROBLEM

Non-linear stability of the libration point L-4 of the restricted thre e-body problem is studied when the more massive primary is an oblate s pheroid with its equatorial plane coincident with the plane of motion. Moser's conditions are utilised in this study by employing the iterat ive scheme of Henrard for transforming the Hamiltonian to the Birkhoff 's normal form with the help of double D'Alembert's series. It is foun d that L-4 is stable for all mass ratios in the range of linear stabil ity except for the three mass ratios: mu(c1)=0.0242...-0.1790...A(1), mu(c2)=0.0135...-0.0993...A(1), mu(c3)=0.0109...-0.0294...A(1).