Dynamics of an isosceles problem generated by a perturbation of Euler's collinear solution
Karine Santos
TL;DR
This work analyzes the linear and parametric stability of a spatial isosceles three-body problem arising from a perturbation of Euler's collinear solution. By transforming to rotating-pulsating coordinates and performing a symplectic reduction anchored by a first integral, the authors obtain a two-degree-of-freedom, time-periodic Hamiltonian with a single equilibrium at $\gamma=1$, and prove its linear stability for $\epsilon=0$ via Dirichlet’s theorem. They then investigate parametric stability under small eccentricity $\epsilon$ and mass ratio $\mu$ using the Krein-Gelfand-Lidskii theorem to identify resonances, and apply Deprit–Hori normalization to construct an autonomous Hamiltonian $K$ up to fourth order, deriving boundary curves in the $(\epsilon,\mu)$ plane from $p(\lambda)=\lambda^4+a\lambda^2+b$. Although several double-resonance scenarios are worked out and explicit curves are presented, the necessary condition $a>0$ cannot be satisfied at the computed order with $b=0$, leaving instability boundaries inconclusive at this level. The results illuminate how resonances shape the parametric stability landscape of isosceles perturbations of Euler's configuration.
Abstract
This paper presents a study of the isosceles problem resulting by a perturbation of Euler's collinear solution under Newtonian gravitational attraction of three bodies in space. After the Hamiltonian was obtained, a circumference of relative equilibria points was found. The original system was subsequently reduced to another system with two degrees of freedom, periodic in the time, where there is now a single point of equilibrium. Linear and parametric stability were discussed in this simplified model of the three-body problem.
