## Abstract

The isosceles three-body problem with nonnegative energy is studied from a variational point of view based on the Jacobi–Maupertuis metric. The solutions are represented by geodesics in the two-dimensional configuration space. Since the metric is singular at collisions, an approach based on the theory of length spaces is used. This provides an alternative to the more familiar approach based on the principle of least action. The emphasis is on the existence and properties of minimal geodesics, that is, shortest curves connecting two points in configuration space. For any two points, even singular points, a minimal geodesic exists and is nonsingular away from the endpoints. For the zero energy case, it is possible to use knowledge of the behavior of the flow on the collision manifold to see that certain solutions must be minimal geodesics. In particular, the geodesic corresponding to the collinear homothetic solution turns out to be a minimal for certain mass ratios.

Original language | English (US) |
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Article number | 48 |

Journal | Qualitative Theory of Dynamical Systems |

Volume | 19 |

Issue number | 1 |

DOIs | |

State | Published - Apr 1 2020 |

### Bibliographical note

Funding Information:This research was supported by NSF Grant DMS-1712656. It was also supported by MSRI, Berkeley, during the semester on Hamiltonian Systems in the Fall of 2019. It benefitted from helpful discussions with R.Montgomery, G. Yu, N. Duignan and C. Jackman. I am grateful to a referee for pointing our several significant errors in the first version of the paper.

Funding Information:

This research was supported by NSF Grant DMS-1712656. It was also supported by MSRI, Berkeley, during the semester on Hamiltonian Systems in the Fall of 2019. It benefitted from helpful discussions with R.Montgomery, G. Yu, N. Duignan and C. Jackman. I am grateful to a referee for pointing our several significant errors in the first version of the paper.

Publisher Copyright:

© 2020, Springer Nature Switzerland AG.

## Keywords

- Celestial mechanics
- Minimal geodesics
- Three-body problem