On dust evolution in planet-forming discs in binary systems – I. Theoretical and numerical modelling: radial drift is faster in binary discs

Monthly Notices of the Royal Astronomical Society, vol. 504, pp. 2235–2252

Abstract

ABSTRACT Many stars are in binaries or higher order multiple stellar systems. Although in recent years a large number of binaries have been proven to host exoplanets, how planet formation proceeds in multiple stellar systems has not been studied much yet from the theoretical standpoint. In this paper, we focus on the evolution of the dust grains in planet-forming discs in binaries. We take into account the dynamics of gas and dust in discs around each component of a binary system under the hypothesis that the evolution of the circumprimary and the circumsecondary discs is independent. It is known from previous studies that the secular evolution of the gas in binary discs is hastened due to the tidal interactions with their hosting stars. Here, we prove that binarity affects dust dynamics too, possibly in a more dramatic way than the gas. In particular, the presence of a stellar companion significantly reduces the amount of solids retained in binary discs because of a faster, more efficient radial drift, ultimately shortening their lifetime. We prove that how rapidly discs disperse depends both on the binary separation, with discs in wider binaries living longer, and on the disc viscosity. Although the less-viscous discs lose high amounts of solids in the earliest stages of their evolution, they are dissipated slowly, while those with higher viscosities show an opposite behaviour. The faster radial migration of dust in binary discs has a striking impact on planet formation, which seems to be inhibited in this hostile environment, unless other disc substructures halt radial drift further in. We conclude that if planetesimal formation were viable in binary discs, this process would take place on very short time-scales.

Authors 3

1. Francesco Zagaria corresponding Aachen Leiden Observatory

   Leiden University · University of Cambridge · University of Pavia · Leiden Observatory · Istituto Universitario di Studi Superiori di Pavia

   Affiliation as printed

   Dipartimento di Fisica, Università degli Studi di Pavia, Via Agostino Bassi 6, I-27100 Pavia, Italy

   Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK

   Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands

   Scuola Universitaria Superiore IUSS Pavia, Piazza della Vittoria 15, I-27100 Pavia, Italy

2. Giovanni P. Rosotti Aachen Leiden Observatory

   Leiden University · University of Leicester · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands

   School of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK

3. Giuseppe Lodato

   University of Milan

   Affiliation as printed

   Dipartimento di Fisica, Università degli Studi di Milano, Via Giovanni Celoria 16, I-20133 Milano, Italy