Kepler-47: A Transiting Circumbinary Multi-Planet System

TL;DR

Kepler-47 is a pioneering discovery of a multi-planet system orbiting a binary star, demonstrating that such systems can host planets within habitable zones, expanding our understanding of planetary system formation.

Contribution

This paper reports the first detailed characterization of a circumbinary multi-planet system, Kepler-47, including its planets' sizes, orbits, and potential habitability.

Findings

Two planets orbiting a binary star system were characterized.

One planet resides within the habitable zone.

The system demonstrates that binary stars can host complete planetary systems.

Abstract

We report the detection of Kepler-47, a system consisting of two planets orbiting around an eclipsing pair of stars. The inner and outer planets have radii 3.0 and 4.6 times that of the Earth, respectively. The binary star consists of a Sun-like star and a companion roughly one-third its size, orbiting each other every 7.45 days. With an orbital period of 49.5 days, eighteen transits of the inner planet have been observed, allowing a detailed characterization of its orbit and those of the stars. The outer planet's orbital period is 303.2 days, and although the planet is not Earth-like, it resides within the classical "habitable zone", where liquid water could exist on an Earth-like planet. With its two known planets, Kepler-47 establishes that close binary stars can host complete planetary systems.