Terrestrial Planets Formation around Circumbinary Habitable Zone: Inward Migration in the Planetesimal Swarm

TL;DR

This study uses numerical simulations to demonstrate that inward migration of planetary embryos in circumbinary systems, driven by planetesimal scattering, can lead to planet formation in habitable zones, highlighting a natural water delivery process.

Contribution

It reveals that embryo migration driven by planetesimal scattering is a robust mechanism for habitable planet formation around circumbinary stars, emphasizing the importance of inner disk mass and embryo interactions.

Findings

Inward migration of embryos is robust in circumbinary systems.

Total mass of inner planetesimals influences migration extent.

Migration acts as a natural water delivery mechanism.

Abstract

According to the core accretion theory, circumbinary embryos can form only beyond a critical semimajor axis (CSMA). However, due to the relatively high density of solid materials in the inner disk, significant amount of small planetesimals must exist in the inner zone when embryos were forming outside this CSMA. So embryos migration induced by the planetesimal swarm is possible after the gas disk depletion. Through numerical simulations, we found (i) the scattering-driven inward migration of embryos is robust, planets can form in the habitable zone if we adopt a mass distribution of MMSN-like disk; (ii) the total mass of the planetesimals in the inner region and continuous embryo-embryo scattering are two key factors that cause significant embryo migrations; (iii) the scattering-driven migration of embryos is a natural water-deliver mechanism. We propose that planet detections should focus on the close binary with its habitable zone near CSMA.