Growth of grains in Brown Dwarf disks

TL;DR

This study models grain growth in brown dwarf disks, demonstrating that large grains can form similarly to T Tauri disks due to comparable collisional timescales, potentially explaining recent millimeter-sized grain observations.

Contribution

It introduces a physically-motivated coagulation and fragmentation model to simulate grain growth in brown dwarf disks, showing comparable growth to T Tauri disks.

Findings

Large grains can grow in brown dwarf disks.

Growth occurs at similar scaled locations in both disk types.

Collisional timescales are comparable in brown dwarf and T Tauri disks.

Abstract

We perform coagulation and fragmentation simulations using the new physically-motivated model by Garaud et al. (2013) to determine growth locally in brown dwarf disks. We show that large grains can grow and that if brown dwarf disks are scaled down versions of T Tauri disks (in terms of stellar mass, disk mass and disk radius) growth at an equivalent location with respect to the disk truncation radius can occur to the same size in both disks. We show that similar growth occurs because the collisional timescales in the two disks are comparable. Our model may therefore potentially explain the recent observations of grain growth to millimetre sizes in brown dwarf disks, as seen in T Tauri disks.