Prediction of an Earth-sized Planet Formed in the Habitable Zone of the SPECULOOS-2 System

Abstract

Transiting planets in the nearby TRAPPIST-1 system provide rare examples of habitable zone (HZ), Earth-sized planets that can be characterized via transmission spectroscopy. However, these present-day HZ planets likely formed interior to HZ and probably underwent an evolution very different from that of Earth. We present the integrative analysis of the planetary architecture of the recently discovered planetary system SPECULOOS-2. Our analysis answers the question: If there are additional exoplanets in the SPECULOOS-2 system, what are their orbital and physical properties? We predict an Earth-sized planet in the habitable zone (P ∼ 14.5–18.2 days). In contrast to TRAPPIST-1e, this predicted planet most likely completed its formation inside the habitable zone. If confirmed, this planet will offer an Earth-sized, habitable zone planet that is likely to have an evolutionary path more similar to Earth than those in the TRAPPIST-1 system.