Celestial dances involving three bodies may occur more frequently in the cosmos than astronomers once believed.
These intricate orbits, known as braids, arise when three objects, such as stars or planets, trace repeating paths that intertwine like strands in a weave, bound by gravity without colliding. Long viewed as rare and exceptional configurations, braids now appear to emerge from everyday gravitational encounters among four bodies, according to a new study published in ArXiv.
The researchers simulated such interactions using computer models of Newtonian gravity, starting with known braid patterns and then introducing a fourth object to disrupt them. By reversing the process and tracing backward from a braid to see how it might form, they discovered that these orbits can develop from collisions between two pairs of orbiting bodies or from a trio encountering a lone wanderer.
A key revelation is that braids form in about 9 percent of the simulated encounters, a surprisingly high rate that challenges prior assumptions about their scarcity. “Since a substantial fraction of ∼9% of our calculations lead to periodic three-body systems, braids may be more common than expected,” the researchers write.
Among the braids examined, three proved stable over long periods, resisting small disturbances, while one was chaotic and short-lived, breaking apart after roughly 40 orbits. The formation process often results in one tight pair and a much wider one, with the orbits stretched into highly elongated shapes.
The study also explores how these braids might behave in real astronomical settings. “We argue that braids are particularly common in relatively shallow-potential background fields, such as the Oort cloud or the Galactic halo,” the team notes, referring to the distant comet reservoir around our solar system and the sparse outer reaches of the Milky Way.
In denser environments, braids tend to dissolve quickly, but in these quieter regions, they could persist as temporary arrangements, lasting tens to hundreds of cycles. The simulations suggest that non-flat, three-dimensional encounters can still produce braids, though the conditions for success cluster in specific angles and velocities, forming irregular patterns in the data.
Adding intrigue, the researchers point out potential consequences for compact objects like black holes or neutron stars. “Braid formation, however, easily leads to collisions between two or more of its constituents. If composed of compact objects, they potentially form interesting targets for gravitational wave detectors,” they explain.
Citations
Simon Portegies Zwart et al. The formation of periodic three-body orbits for Newtonian systems. ArXiv. Published online January 14, 2026. DOI: 10.48550/arXiv.2601.09843
