VLA observations of the disk around the young brown dwarf 2MASS J044427+2512

TL;DR

This study uses VLA radio observations to analyze the disk around the young brown dwarf 2MASS J04442713+2512164, revealing dust and ionized gas emissions, and tests dust evolution models in a gas-rich environment.

Contribution

It provides the first detailed multi-wavelength radio analysis of a brown dwarf disk, testing dust evolution models and discussing ionized gas emission mechanisms.

Findings

Detection of dust thermal emission at 6.8 and 9.1 mm

Ionized gas emission dominates at 1.36 cm

Dust evolution models require slowed radial drift or pressure bumps

Abstract

We present multi-wavelength radio observations obtained with the VLA of the protoplanetary disk surrounding the young brown dwarf 2MASS J04442713+2512164 (2M0444) in the Taurus star forming region. 2M0444 is the brightest known brown dwarf disk at millimeter wavelengths, making this an ideal target to probe radio emission from a young brown dwarf. Thermal emission from dust in the disk is detected at 6.8 and 9.1 mm, whereas the 1.36 cm measured flux is dominated by ionized gas emission. We combine these data with previous observations at shorter sub-mm and mm wavelengths to test the predictions of dust evolution models in gas-rich disks after adapting their parameters to the case of 2M0444. These models show that the radial drift mechanism affecting solids in a gaseous environment has to be either completely made inefficient, or significantly slowed down by very strong gas pressure bumps in order to explain the presence of mm/cm-sized grains in the outer regions of the 2M0444 disk. We also discuss the possible mechanisms for the origin of the ionized gas emission detected at 1.36 cm. The inferred radio luminosity for this emission is in line with the relation between radio and bolometric luminosity valid for for more massive and luminous young stellar objects, and extrapolated down to the very low luminosity of the 2M0444 brown dwarf.