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arXiv · 2509.07930

Particle dynamics in TOI-178 planetary system

J. Boskovic·R. Sfair·C. M. Schäfer
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Abstract

The TOI-178 system hosts six planets with five of them locked in a :4:6:9:12 Laplace resonance chain. We perform N-body simulations to investigate the dynamics of test particles in this system. We observe that co-orbital regions around each planet are approximately 30\% wider than predicted by classical theory for planets in the resonance chain, while TOI-178b, which lies outside the chain, shows a 52\% enhancement. The region between TOI-178e and TOI-178f reveals Kirkwood gap-like structures created by mean-motion resonances with TOI-178f (4:3, 5:4, 6:5) and TOI-178g (5:3), where particle clearing occurs on 500-year timescales. An extended integration of the innermost region (0.015-0.025 au) shows periodic inclination oscillations with period 196 years, coincident with TOI-178b's own oscillation period, with maximum amplitude occurring near the 3:2 resonance location. These structures are consistent with the system's resonant architecture and provide a baseline characterization that enables future comparative studies of similar phenomena in other multi-planet systems with resonant configurations.

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J. Boskovic, R. Sfair, C. M. Schäfer. 2025-09-09. Particle dynamics in TOI-178 planetary system. https://doi.org/10.1140/epjs%2Fs11734-025-01915-2

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