Formation of massive planets in binary star systems

TL;DR

This paper investigates how the presence of a secondary star in binary systems influences planet formation, using hydrodynamical simulations to analyze disk dynamics and protoplanet evolution, with a focus on the Gamma Cephei system.

Contribution

It provides new insights into the dynamical effects of binary companions on circumstellar disks and planet formation processes through detailed hydrodynamical simulations.

Findings

Disks become eccentric and precess around the primary star.

Protoplanet orbital evolution is significantly affected by binary dynamics.

Mass growth of protoplanets is influenced by the binary environment.

Abstract

As of today over 40 planetary systems have been discovered in binary star systems. In all cases the configuration appears to be circumstellar, where the planets orbit around one of the stars, the secondary acting as a perturber. The formation of planets in binary star systems is more difficult than around single stars due to the gravitational action of the companion on the dynamics of the protoplanetary disk. In this contribution we first briefly present the relevant observational evidence for planets in binary systems. Then the dynamical influence that a secondary companion has on a circumstellar disk will be analyzed through fully hydrodynamical simulations. We demonstrate that the disk becomes eccentric and shows a coherent precession around the primary star. Finally, fully hydrodynamical simulations of evolving protoplanets embedded in disks in binary star systems are presented. We investigate how the orbital evolution of protoplanetary embryos and their mass growth from cores to massive planets might be affected in this very dynamical environment. We consider, in particular, the planet orbiting the primary in the system Gamma Cephei.