Degeneracy of Planar Central Configurations in the $N$-Body Problem

Fuente: arXiv
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Autori principali: Sun, Shanzhong, Xie, Zhifu, You, Peng
Natura: Preprint
Pubblicazione: 2025
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author Sun, Shanzhong
Xie, Zhifu
You, Peng
author_facet Sun, Shanzhong
Xie, Zhifu
You, Peng
contents The degeneracy of central configurations in the planar $N$-body problem makes their enumeration problem hard and the related dynamics appealing. To truly understand the bifurcations of central configurations, we should work in the FULL configuration space which also facilitates the computer-aided methods. The degeneracy is always intertwined with the symmetry of the system of central configurations which makes the problem subtle. By analyzing the Jacobian matrix of the system, we systematically explore the direct method to single out trivial zero eigenvalues associated with translational, rotational and scaling symmetries, thereby isolating the non-trivial part of the Jacobian to study the degeneracy. Four distinct formulations of degeneracy are presented, each tailored to handle different forms of the system appeared in the literature. The method is applied to such well-known examples as Lagrange's equilateral triangle solutions for arbitrary masses, the square configuration for four equal masses and the equilateral triangle with a central mass revealing specific mass values for which degeneracy occurs. Combining with the interval algorithm, the nondegeneracy of rhombus central configurations for arbitrary mass is also established.
format Preprint
id arxiv_https___arxiv_org_abs_2510_25649
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Degeneracy of Planar Central Configurations in the $N$-Body Problem
Sun, Shanzhong
Xie, Zhifu
You, Peng
Dynamical Systems
Mathematical Physics
70F10, 70F15
The degeneracy of central configurations in the planar $N$-body problem makes their enumeration problem hard and the related dynamics appealing. To truly understand the bifurcations of central configurations, we should work in the FULL configuration space which also facilitates the computer-aided methods. The degeneracy is always intertwined with the symmetry of the system of central configurations which makes the problem subtle. By analyzing the Jacobian matrix of the system, we systematically explore the direct method to single out trivial zero eigenvalues associated with translational, rotational and scaling symmetries, thereby isolating the non-trivial part of the Jacobian to study the degeneracy. Four distinct formulations of degeneracy are presented, each tailored to handle different forms of the system appeared in the literature. The method is applied to such well-known examples as Lagrange's equilateral triangle solutions for arbitrary masses, the square configuration for four equal masses and the equilateral triangle with a central mass revealing specific mass values for which degeneracy occurs. Combining with the interval algorithm, the nondegeneracy of rhombus central configurations for arbitrary mass is also established.
title Degeneracy of Planar Central Configurations in the $N$-Body Problem
topic Dynamical Systems
Mathematical Physics
70F10, 70F15
url https://arxiv.org/abs/2510.25649