Giant planets: good neighbors for habitable worlds?

TL;DR

This paper investigates how giant planets influence the habitability of terrestrial worlds, showing that they can both hinder and, in some cases, slightly enhance habitable zones depending on system dynamics.

Contribution

It provides a comprehensive analysis of 147 exoplanetary systems, quantifying the impact of giant planets on the habitability potential of terrestrial planets.

Findings

Giant planets often reduce habitable zone sizes in systems.

In some cases, giant planets can slightly expand habitable zones.

High climate inertia in terrestrial planets can mitigate negative effects.

Abstract

The presence of giant planets influences potentially habitable worlds in numerous ways. Massive celestial neighbors can facilitate the formation of planetary cores and modify the influx of asteroids and comets towards Earth-analogs later on. Furthermore, giant planets can indirectly change the climate of terrestrial worlds by gravitationally altering their orbits. Investigating 147 well characterized exoplanetary systems known to date that host a main sequence star and a giant planet we show that the presence of 'giant neighbors' can reduce a terrestrial planet's chances to remain habitable, even if both planets have stable orbits. In a small fraction of systems, however, giant planets slightly increase the extent of habitable zones provided the terrestrial world has a high climate inertia. In providing constraints on where giant planets cease to affect the habitable zone size in a detrimental fashion, we identify prime targets in the search for habitable worlds.