Prospecting for exo-Earths in multiple planet systems with a gas giant

TL;DR

This study identifies promising exoplanet systems with gas giants where stable, detectable Earth-like planets could exist in the habitable zone, using numerical simulations and radial velocity predictions.

Contribution

It introduces a method to find stable, potentially habitable Earth-mass planets in systems with gas giants, considering complex gravitational interactions.

Findings

16 candidate systems identified for hosting stable exo-Earths

Secular resonances significantly influence habitable zone stability

Radial velocity signals of Earth-mass planets are detectable with ESPRESSO

Abstract

In this work, we hunt for the best places to find exo-Earths in the currently known exoplanet population. While it is still unclear whether Jupiter had a beneficial or detrimental effect on the creation of the right environment for a habitable Earth to develop, we focus on the 51 multiple planet systems that have at least one Jupiter-like planet and aim to identify which would be good candidates to host an exo-Earth. We conduct a series of numerical simulations to identify dynamically stable regions of the habitable zone of the multiple exoplanet systems capable of hosting an Earth-mass planet. We produce a candidate list of 16 systems that could host such a stable exo-Earth in their habitable zone, and for which the induced radial velocity signal of a hypothetical one, two or four Earth-mass planet on the host star would be detectable with the ESPRESSO spectrograph. We find that whilst the gravitational interactions with the massive planet nearest the habitable zone are critical in determining stability, the secular resonant interactions between multiple planets can also have a dramatic influence on the overall stability of the habitable zone.