Interior and Climate Modeling of the Venus Zone Planet TOI-2285 b

TL;DR

This study models the interior and climate of exoplanet TOI-2285 b, exploring its potential for temperate conditions and assessing its atmospheric characteristics despite its position in the Venus Zone.

Contribution

It provides the first detailed interior and climate modeling of TOI-2285 b, including volatile estimates and climate scenarios using ROCKE-3D, and assesses its observability with JWST.

Findings

Temperate climate scenarios are possible for TOI-2285 b.

Planet may have a steam atmosphere despite its Venus Zone location.

JWST could detect atmospheric features under certain conditions.

Abstract

As the discovery of exoplanets progresses at a rapid pace, the large number of known planets provides a pathway to assess the stellar and planetary properties that govern the climate evolution of terrestrial planets. Of particular interest are those planetary cases that straddle the radius boundary of being terrestrial or gaseous in nature, such as super-Earth and sub-Neptune exoplanets, respectively. The known exoplanet, TOI-2285 b, is one such case, since it lies at the radius boundary of super-Earth and sub-Neptune ($R_p = 1.74$ $R_\oplus$), and receives a relatively high instellation flux since its orbit exists within both the Habitable Zone (HZ) and Venus Zone (VZ). Here, we present an analysis of the planetary interior and climate to determine possible evolutionary pathways for the planet. We provide volatile inventory estimates in terms of the planet's bulk density and interior composition. We performed climate simulations using ROCKE-3D that provide a suite of possible temperate scenarios for the planet for a range of topographical and initial surface water assumptions. Using the outputs of the climate simulations, we modeled JWST transmission and emission spectroscopy for each scenario. Our results demonstrate that there are temperate scenarios consistent with the known planetary properties, despite the planet's estimated steam atmosphere, and its location relative to the VZ.