# ALMA Observations of the Young Substellar Binary System 2M1207

## TL;DR

This study uses ALMA to observe the 2M1207 binary system, revealing a compact disk around the brown dwarf and setting tight limits on dust around its planetary companion, informing planet formation models.

## Contribution

First ALMA detection of dust and CO emission from a young brown dwarf's disk in a binary system with a planetary companion, providing new constraints on circum-planetary material.

## Key findings

- Detected dust continuum and CO emission from the brown dwarf's disk.
- Estimated dust mass of 0.1 Earth masses for the brown dwarf's disk.
- Set an upper limit of ~1 Moon mass for dust around the planetary companion.

## Abstract

We present ALMA observations of the 2M1207 system, a young binary made of a brown dwarf with a planetary-mass companion at a projected separation of about 40 au. We detect emission from dust continuum at 0.89 mm and from the $J = 3 - 2$ rotational transition of CO from a very compact disk around the young brown dwarf. The small radius found for this brown dwarf disk may be due to truncation from the tidal interaction with the planetary-mass companion. Under the assumption of optically thin dust emission, we estimated a dust mass of 0.1 $M_{\oplus}$ for the 2M1207A disk, and a 3$\sigma$ upper limit of $\sim 1~M_{\rm{Moon}}$ for dust surrounding 2M1207b, which is the tightest upper limit obtained so far for the mass of dust particles surrounding a young planetary-mass companion. We discuss the impact of this and other non-detections of young planetary-mass companions for models of planet formation, which predict the presence of circum-planetary material surrounding these objects.