# An upper limit on the mass of the circumplanetary disk for DH Tau b

## TL;DR

This study constrains the dust mass of the circumplanetary disk around DH Tau b using NOEMA observations, finding it to be very low, which impacts theories of planet formation around young stars.

## Contribution

It provides the first upper limit on the circumplanetary disk mass for DH Tau b, combining observational data with radiative transfer modeling to refine mass estimates.

## Key findings

- Disk dust mass for DH Tau A is approximately 17.2 Earth masses.
- Upper limit for DH Tau b's disk dust mass is about 0.09 Earth masses.
- Results suggest very low circumplanetary disk mass, influencing planet formation theories.

## Abstract

DH Tau is a young ($\sim$1 Myr) classical T Tauri star. It is one of the few young PMS stars known to be associated with a planetary mass companion, DH Tau b, orbiting at large separation and detected by direct imaging. DH Tau b is thought to be accreting based on copious H${\alpha}$ emission and exhibits variable Paschen Beta emission. NOEMA observations at 230 GHz allow us to place constraints on the disk dust mass for both DH Tau b and the primary in a regime where the disks will appear optically thin. We estimate a disk dust mass for the primary, DH Tau A of $17.2\pm1.7\,M_{\oplus}$, which gives a disk-to-star mass ratio of 0.014 (assuming the usual Gas-to-Dust mass ratio of 100 in the disk). We find a conservative disk dust mass upper limit of 0.42$M_{\oplus}$ for DH Tau b, assuming that the disk temperature is dominated by irradiation from DH Tau b itself. Given the environment of the circumplanetary disk, variable illumination from the primary or the equilibrium temperature of the surrounding cloud would lead to even lower disk mass estimates. A MCFOST radiative transfer model including heating of the circumplanetary disk by DH Tau b and DH Tau A suggests that a mass averaged disk temperature of 22 K is more realistic, resulting in a dust disk mass upper limit of 0.09$M_{\oplus}$ for DH Tau b. We place DH Tau b in context with similar objects and discuss the consequences for planet formation models.