On the Habitable Zones of Circumbinary Planetary Systems

TL;DR

This paper derives habitable zone boundaries for circumbinary systems, considering stellar properties and orbital dynamics, and compares these with single-star models to identify when simplifications are valid.

Contribution

It introduces a method to determine habitable zones in circumbinary systems accounting for binary motion and applies it to known systems, highlighting limitations of single-star approximations.

Findings

HZ boundaries depend on stellar masses, separation, and time.

Stability regimes for planetary orbits are identified.

Single-star HZ models often break down in binary systems.

Abstract

The effect of the stellar flux on exoplanetary systems is becoming an increasingly important property as more planets are discovered in the Habitable Zone (HZ). The Kepler mission has recently uncovered circumbinary planets with relatively complex HZs due to the combined flux from the binary host stars. Here we derive HZ boundaries for circumbinary systems and show their dependence on the stellar masses, separation, and time while accounting for binary orbital motion and the orbit of the planet. We include stability regimes for planetary orbits in binary systems with respect to the HZ. These methods are applied to several of the known circumbinary planetary systems such as Kepler-16, 34, 35, and 47. We also quantitatively show the circumstances under which single-star approximations break down for HZ calculations.