Vertical Structure and Turbulent Saturation Level in Fully Radiative Protoplanetary Disc Models

TL;DR

This study uses 3D radiation magnetohydrodynamics simulations to explore the vertical structure and turbulence saturation in a fully radiative protoplanetary disc, revealing a self-consistent balance between heating and cooling.

Contribution

It provides the first detailed analysis of the vertical structure and turbulence saturation levels in fully radiative protoplanetary discs using high-resolution 3D simulations.

Findings

The disc has a gas-pressure dominated midplane and a magnetically dominated corona.

Turbulence at the photosphere is supersonic with Mach number around 2.

Saturation levels and heating rates converge with sufficient resolution.

Abstract

We investigate a massive ($\varSigma \sim 10000 g cm^{-2}$ at 1 AU) protoplanetary disc model by means of 3D radiation magnetohydrodynamics simulations. The vertical structure of the disc is determined self-consistently by a balance between turbulent heating caused by the MRI and radiative cooling. Concerning the vertical structure, two different regions can be distinguished: A gas-pressure dominated, optically thick midplane region where most of the dissipation takes place, and a magnetically dominated, optically thin corona which is dominated by strong shocks. At the location of the photosphere, the turbulence is supersonic ($M \sim 2$), which is consistent with previous results obtained from the fitting of spectra of YSOs. It is known that the turbulent saturation level in simulations of MRI-induced turbulence does depend on numerical factors such as the numerical resolution and the box size. However, by performing a suite of runs at different resolutions (using up to 64x128x512 grid cells) and with varying box sizes (with up to 16 pressure scaleheights in the vertical direction), we find that both the saturation levels and the heating rates show a clear trend to converge once a sufficient resolution in the vertical direction has been achieved.