A Herschel Search For Cold Dust in Brown Dwarf Disks: First Results

TL;DR

This study uses Herschel observations to detect cold dust in brown dwarf disks, revealing substantial outer disk material and providing new constraints on disk masses around young brown dwarfs.

Contribution

First detection of cold dust emission at 160 microns in brown dwarf disks, enabling better estimates of disk mass and structure.

Findings

Detected cold dust in all three surveyed brown dwarfs at 70 microns.

First brown dwarf detection at 160 microns, indicating significant outer disk material.

Estimated disk masses range from a few 10^-6 to 10^-4 solar masses.

Abstract

We report initial results from a {\it Herschel} program to search for far-infrared emission from cold dust around a statistically significant sample of young brown dwarfs. The first three objects in our survey are all detected at 70\micron, and we report the first detection of a brown dwarf at 160\micron. The flux densities are consistent with the presence of substantial amounts of cold dust in the outer disks around these objects. We modeled the SED's with two different radiative transfer codes. We find that a broad range of model parameters provides a reasonable fit to the SED's, but that the addition of our 70\micron, and especially the 160\micron\ detection enables strong lower limits to be placed on the disk masses since most of the mass is in the outer disk. We find likely disk masses in the range of a few $\times 10^{-6}$ to $10^{-4}$ \msun. Our models provide a good fit to the SED's and do not require dust settling.