Complex Molecule Formation in Grain Mantles

TL;DR

This study demonstrates that grain surface chemistry, combined with gas phase processes, can explain the observed abundances of complex molecules in hot molecular cores and corinos, which gas phase models alone cannot account for.

Contribution

The paper introduces a comprehensive model including both gas and grain surface chemistry to explain complex molecule formation in hot core environments.

Findings

Grain surface processing is essential for producing observed complex molecules.

Model results match observed molecular abundances in various core scenarios.

Differences in abundances depend on initial composition and collapse timescales.

Abstract

Context: Complex molecules such as ethanol and dimethyl ether have been observed in a number of hot molecular cores and hot corinos. Attempts to model the molecular formation process using gas phase only models have so far been unsuccessful. Aims : To demonstrate that grain surface processing is a viable mechanism for complex molecule formation in these environments. Methods: A variable environment parameter computer model has been constructed which includes both gas and surface chemistry. This is used to investigate a variety of cloud collapse scenarios. Results: Comparison between model results and observation shows that by combining grain surface processing with gas phase chemistry complex molecules can be produced in observed abundances in a number of core and corino scenarios. Differences in abundances are due to the initial atomic and molecular composition of the core/corino and varying collapse timescales. Conclusions: Grain surface processing, combined with variation of physical conditions, can be regarded as a viable method for the formation of complex molecules in the environment found in the vicinity of a hot core/corino and produce abundances comparable to those observed.