Brown dwarfs forming in discs: where to look for them?

TL;DR

This paper investigates the formation of brown dwarfs through disc fragmentation, using simulations to predict their properties and distribution, and suggests observational strategies for detecting these objects.

Contribution

It provides the first statistical analysis of low-mass objects formed by disc fragmentation, highlighting the existence of wide-orbit brown dwarfs around Sun-like stars.

Findings

Brown dwarfs formed by disc fragmentation tend to be on wide orbits (100-5000 AU).

Planetary-mass companions are unlikely to form via disc fragmentation.

The model explains the brown dwarf desert and binary properties of low-mass objects.

Abstract

A large fraction of the observed brown dwarfs may form by gravitational fragmentation of unstable discs. This model reproduces the brown dwarf desert, and provides an explanation the existence of planetary-mass objects and for the binary properties of low-mass objects. We have performed an ensemble of radiative hydrodynamic simulations and determined the statistical properties of the low-mass objects produced by gravitational fragmentation of discs. We suggest that there is a population of brown dwarfs loosely bound on wide orbits (100-5000 AU) around Sun-like stars that surveys of brown dwarf companions should target. Our simulations also indicate that planetary-mass companions to Sun-like stars are unlikely to form by disc fragmentation.