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Figure-8 satellite HS.87

From Hristov, Hristova & Tanikawa (2026)

Figure-8 satellite HS.87 is a periodic orbit of the planar three-body problem: three equal masses that return to their starting positions and velocities every 251.99 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 0.445 of each other at a top speed of 1.64, line up 162 times a period, and the computed loop closes to 3.2×10⁻²⁸.

Measured over one period

Period: 251.9913168
Masses: 1 : 1 : 1
Energy: -0.992576
Angular momentum: 0
Closest approach: 0.4449
Top speed: 1.637
Path length: 564.29
Alignments per period: 162
Topology: (abAB)²⁷ (free-group class)
Stability: stable (|λ|max 1.000, published)
Loop closure: 3.2×10⁻²⁸

Neighbours on the map

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