Eccentricity Driven Climate Effects in the Kepler-1649 System

TL;DR

This paper investigates how eccentricity variations in the Kepler-1649 system influence planetary climate stability, revealing that planets can sustain stable climates despite significant eccentricity oscillations, offering insights into diverse exoplanetary climate evolution.

Contribution

The study presents dynamical and climate simulations showing stable planetary climates under high eccentricity oscillations in the Kepler-1649 system, highlighting potential for diverse climate evolution pathways.

Findings

Eccentricity oscillations occur on 1000-3000 year timescales.

Planets can maintain stable climates despite large eccentricity variations.

Dynamically viable regions exist for additional terrestrial planets between known planets.

Abstract

The discovery of terrestrial exoplanets is uncovering increasingly diverse architectures. Of particular interest are those systems that contain exoplanets at a variety of star-planet separations, allowing direct comparison of exoplanet evolution (comparative planetology). The Kepler-1649 system contains two terrestrial planets similar both in size and insolation flux to Venus and Earth, although their eccentricities remain largely unconstrained. Here we present results of dynamical studies of the system and the potential effects on climate. The eccentricities of the Kepler-1649 system are poorly constrained, and we show that there are dynamically viable regions for further terrestrial planets in between the two known planets for a limited range of eccentricities. We investigate the effect of eccentricity of the outer planet on the dynamics of both planets and show that this results in high-frequency (1000-3000 year) eccentricity oscillations in long-term stable configurations. We calculate the resulting effect of these eccentricity variations on insolation flux and present the results of 3D climate simulations for the habitable zone planet. Our simulations demonstrate that, despite large eccentricity variations, the planet can maintain stable climates with relatively small temperature variations on the substellar hemisphere for a variety of initial climate configurations. Such systems thus provide key opportunities to explore alternative Venus/Earth climate evolution scenarios.