Effects of Flux Variation on the Surface Temperatures of Earth-like Circumbinary Planets

TL;DR

This study investigates how flux variation caused by binary star dynamics affects the surface temperatures and habitability of Earth-like circumbinary planets, revealing they are generally warmer than single-star analogs due to flux redistribution and feedback mechanisms.

Contribution

It introduces a detailed analysis of flux and temperature evolution in Earth-like circumbinary planets, highlighting the significant role of binary dynamics and feedback in habitability.

Findings

Flux variation peaks at a mass ratio of ~0.3 for G-K binaries.

Ice-albedo feedback significantly influences habitability.

CBP analogs are generally warmer than single-star equivalents.

Abstract

The Kepler Space telescope has uncovered around thirteen circumbinary planets (CBPs) that orbit a pair of stars and experience two sources of stellar flux. We characterize the top-of-atmosphere flux and surface temperature evolution in relation to the orbital short-term dynamics between the central binary star and an Earth-like CBP analog. We compare the differential evolution of an Earth-like CBP's flux and surface temperature with that of an equivalent single-star (ESS) system to uncover the degree by which the potential habitability of the planet could vary. For a Sun-like primary, we find that the flux variation over a single planetary orbit is greatest when the dynamical mass ratio is ~0.3 for a G-K spectral binary. Using a latitudinal energy balance model, we show that the ice-albedo feedback plays a substantial role in Earth-like CBP habitability due to the interplay between flux redistribution (via obliquity) and changes in the total flux (via binary gyration). We examine the differential evolution of flux and surface temperature for Earth-like analogs of the habitable zone CBPs (4 Kepler and 1 hypothetical system) and find that these analogs are typically warmer than their ESS counterparts.