# Hydrodynamic Photoevaporation of Protoplanetary Disks with Consistent Thermochemistry

## TL;DR

This study uses advanced hydrodynamic simulations with thermochemistry to analyze how ultraviolet and X-ray radiation drive photoevaporative winds in protoplanetary disks, revealing detailed wind structures and chemical reformation processes.

## Contribution

It introduces a comprehensive simulation approach combining hydrodynamics, radiative transfer, and thermochemistry to study disk photoevaporation with consistent chemistry modeling.

## Key findings

- Most models show a three-layer disk structure with a hot wind at ~30 km/s.
- Reformation of molecules like CO, OH, and H2O occurs in the intermediate layer.
- Mass-loss rates depend on radiation intensity and modeling assumptions.

## Abstract

Photoevaporation is an important dispersal mechanism for protoplanetary disks. We conduct hydrodynamic simulations coupled with ray-tracing radiative transfer and consistent thermochemistry to study photoevaporative winds driven by ultraviolet and X-ray radiation from the host star. Most models have a three-layer structure: a cold midplane, warm intermediate layer, and hot wind, the last having typical speeds $\sim 30~\mathrm{km\ s}^{-1}$ and mass-loss rates $\sim 10^{-9}~M_\odot~\mathrm{yr}^{-1}$ when driven primarily by ionizing UV radiation. Observable molecules including CO, OH and H2O re-form in the intermediate layer and survive at relatively high wind temperatures due to reactions being out of equilibrium. Mass-loss rates are sensitive to the intensity of radiation in energy bands that interact directly with hydrogen. Comparison with previous works shows that mass loss rates are also sensitive to the treatment of both the hydrodynamics and the thermochemistry. Divergent results concerning the efficiency of X-ray photoevaporation are traced in part to differing assumptions about dust and other coolants.