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Figure-8 satellite HS.684

From Hristov, Hristova & Tanikawa (2026)

Figure-8 satellite HS.684 is a periodic orbit of the planar three-body problem: three equal masses that return to their starting positions and velocities every 342.96 time units, published by Hristov, Hristova & Tanikawa (2026). Stable orbits found by an exhaustive search of the figure-eight’s neighbourhood: each traces the eight with extra loops and twists, and every one is linearly stable to 40 digits. It is linearly stable (largest Floquet multiplier 1.000), so a small nudge only makes it wobble. The bodies pass within 0.237 of each other at a top speed of 2.22, line up 444 times a period, and the computed loop closes to 3.3×10⁻²⁸.

Measured over one period

Period: 342.9595538
Masses: 1 : 1 : 1
Energy: -1.58311
Angular momentum: 0
Closest approach: 0.2369
Top speed: 2.218
Path length: 974.17
Alignments per period: 444
Topology: (abAB)⁷⁴ (free-group class)
Stability: stable (|λ|max 1.000, published)
Loop closure: 3.3×10⁻²⁸

Neighbours on the map

All Figure-8 satellites, the families of periodic three-body orbits, or the atlas map.