Is the orbital distribution of multiplanet systems influenced by pure three-planet resonances?

TL;DR

This study investigates how the distribution of multi-planet systems relates to resonance structures, suggesting a potential causal link influenced by planetary migration or damping processes.

Contribution

It provides the first statistical analysis linking multi-planet system distributions to pure three-planet resonances, highlighting their possible role in system architecture.

Findings

Significant correlation between system distribution and resonance web.

Resonance chains contribute strongly but are not the sole factor.

Implications for planetary migration and damping in system formation.

Abstract

We analyze the distribution of known multi-planet systems ($N \geq 3$) in the plane of mean-motion ratios, and compare it with the resonance web generated by two-planet mean-motion resonances (2P-MMR) and pure 3-planet commensurabilities (pure 3P-MMR). We find intriguing evidence of a statistically significant correlation between the observed distribution of compact low-mass systems and the resonance structure, indicating a possible causal relation. While resonance chains such as Kepler-60, Kepler-80 and TRAPPIST-1 are strong contributors, most of the correlation appears to be caused by systems not identified as resonance chains. Finally, we discuss their possible origin through planetary migration during the last stages of the primordial disc and/or an eccentricity damping process.