Eccentricity Evolution of Warm Jupiters: The Role of Distant Perturbers and Nearby Companions

TL;DR

This paper investigates how distant giant planets and nearby low-mass companions influence the eccentricity evolution of warm Jupiters, revealing a bimodal distribution driven by dynamical interactions and orbital configurations.

Contribution

It presents the first comprehensive N-body simulation study showing how distant perturbers and nearby companions jointly shape warm Jupiters' eccentricities, explaining observed distributions.

Findings

Distant perturbers can induce large eccentricity oscillations via the von Zeipel-Lidov-Kozai mechanism.

Nearby super-Earths often suppress eccentricity variations through dynamical coupling.

Observed eccentricity distribution suggests many perturbers have extreme orbits with high inclinations or eccentricities.

Abstract

Warm Jupiters-giant exoplanets with orbital periods between 10 and 200 days-exhibit a broad range of eccentricities and are often accompanied by nearby low-mass planets. Understanding the origins of their orbital architectures requires examining both their migration histories and subsequent dynamical interactions. In this study, we perform extensive N-body simulations to explore how distant giant planet perturbers affect the eccentricity evolution of warm Jupiters and the role of nearby super-Earth companions in mediating these interactions. We find that while distant perturbers can induce large-amplitude eccentricity oscillations in warm Jupiters via the von Zeipel-Lidov-Kozai mechanism, the presence of nearby super-Earth companions often suppresses these variations via strong dynamical coupling. This mechanism naturally leads to a bimodal eccentricity distribution: warm Jupiters with nearby companions tend to maintain low eccentricities, whereas those without exhibit significantly broader eccentricity distributions. We show that reproducing the observed eccentricity distribution of warm Jupiters lacking nearby companions is most naturally explained if a substantial fraction of distant perturbers occupy dynamically extreme orbits, either with large mutual inclinations or high orbital eccentricities. These results support a scenario in which warm Jupiters experience substantial post-disk dynamical evolution, shaped jointly by distant perturbers and nearby companions.