The TROY project: II. Multi-technique constraints on exotrojans in nine planetary systems

TL;DR

This study combines multiple observational techniques to search for exotrojans in nine exoplanet systems, setting upper mass limits and finding no definitive evidence of such bodies.

Contribution

It introduces a multi-technique observational approach to constrain the existence of planet-size exotrojans in close-in exoplanet systems.

Findings

No clear evidence of exotrojans in the nine systems.

Upper mass limits in the super-Earth regime for six systems.

Constraints on trojan parameters based on combined observational data.

Abstract

Co-orbital bodies are the byproduct of planet formation and evolution, as we know from the Solar System. Although planet-size co-orbitals do not exists in our planetary system, dynamical studies show that they can remain stable for long periods of time in the gravitational well of massive planets. Should they exist, their detection is feasible with the current instrumentation. In this paper, we present new ground-based observations searching for these bodies co-orbiting with nine close-in (P<5 days) planets, using different observing techniques. The combination of all of them allows us to restrict the parameter space of any possible trojan in the system. We use multi-technique observations (radial velocity, precision photometry and transit timing variations), both newly acquired in the context of the TROY project and publicly available, to constrain the presence of planet-size trojans in the Lagrangian points of nine known exoplanets. We find no clear evidence of trojans in these nine systems through any of the techniques used down to the precision of the observations. However, this allows us to constrain the presence of any potential trojan in the system, specially in the trojan mass/radius versus libration amplitude plane. In particular, we can set upper mass limits in the super-Earth mass regime for six of the studied systems.