Planetesimal collisions in binary systems

TL;DR

This study investigates whether km-sized planetesimals can grow into larger bodies in tight binary star systems despite gravitational perturbations, using numerical simulations of their collisional evolution.

Contribution

It introduces a two-dimensional numerical model that simulates the collisional and accretional evolution of planetesimals in binary systems, considering debris dynamics.

Findings

Planetesimals can grow significantly if formation efficiency is low.

Growth by two orders of magnitude is possible under certain conditions.

Limitations of the 2D approach are discussed.

Abstract

We study the collisional evolution of km-sized planetesimals in tight binary star systems to investigate whether accretion towards protoplanets can proceed despite the strong gravitational perturbations from the secondary star. The orbits of planetesimals are numerically integrated in two dimensions under the influence of the two stars and gas drag. The masses and orbits of the planetesimals are allowed to evolve due to collisions with other planetesimals and accretion of collisional debris. In addition, the mass in debris can evolve due to planetesimal-planetesimal collisions and the creation of new planetesimals. We show that it is possible in principle for km-sized planetesimals to grow by two orders of magnitude in size if the efficiency of planetesimal formation is relatively low. We discuss the limitations of our two-dimensional approach.