Effects of accretion flow on the chemical structure in the inner regions of protoplanetary disks

TL;DR

This study investigates how accretion flows influence molecular abundances and line emissions, especially methanol, in the hot inner regions of protoplanetary disks, highlighting potential observational diagnostics.

Contribution

It models the chemical effects of accretion flow on molecular profiles, emphasizing methanol as a diagnostic tool for accretion velocities in disks.

Findings

High accretion velocities maintain elevated methanol abundances.

Methanol line emission can diagnose accretion flow properties.

Molecular abundance profiles depend on accretion flow dynamics.

Abstract

We have studied the dependence of the profiles of molecular abundances and line emission on the accretion flow in the hot ($\ga 100$K) inner region of protoplanetary disks. The gas-phase reactions initiated by evaporation of the ice mantle on dust grains are calculated along the accretion flow. We focus on methanol, a molecule that is formed predominantly through the evaporation of warm ice mantles, to show how the abundance profile and line emission depend on the accretion flow. Our results show that some evaporated molecules keep high abundances only when the accretion velocity is large enough, and that methanol could be useful as a diagnostic of the accretion flow by means of ALMA observations at the disk radius of $\la 10$AU.