Dynamical Interactions and Habitability in the TOI-700 Multi-Planet System

TL;DR

This study assesses the long-term habitability of the multi-planet system TOI-700, focusing on the dynamics and potential for surface oceans on planets TOI-700d and e, using planetary evolution modeling.

Contribution

It provides the first detailed analysis of orbital dynamics and habitability potential for both planets in the TOI-700 system, considering planet-planet interactions.

Findings

Multi-planet interactions do not prevent habitability.

TOI-700e is near the boundary of the tidally locked habitable zone.

Both planets could potentially retain surface oceans over Gyr timescales.

Abstract

The discovery of a second earth sized planet (TOI-700e) interior to the habitable candidate TOI-700d has prompted further research into this system, as the additional planet makes the TOI-700 system a tightly packed multi-planet system with multiple planets in the habitable zone, like TRAPPIST-1. In this work, we use the planetary evolution code VPLanet to assess the potential habitability of TOI-700d and TOI-700e. We first examine their orbital dynamics to evaluate the influence of planet-planet interactions on the planet spin, obliquity, and eccentricity. We then investigate whether these interactions are sufficient to cause either TOI-700d or e to be perturbed out of a habitable state, and whether we expect either planet could retain surface oceans over Gyr timescales. Together, these analyses allow us to assess the long-term habitability prospects of both TOI-700d and TOI-700e. We find that multi-planet interactions in the TOI-700 system do not prevent either planet from potentially retaining habitable conditions; however, we find that TOI-700e is located very near the boundary of the tidally locked habitable zone (arXiv:1705.10362), suggesting further work is needed to determine whether it is truly habitable.