Overview of complex organic molecule observations in protostellar systems

TL;DR

This review summarizes recent advances in observing complex organic molecules in protostellar systems, highlighting the importance of ice chemistry and the variability of molecular ratios across different objects.

Contribution

It provides a comprehensive overview of gas and ice observations of COMs, emphasizing the role of ice chemistry and the need to consider physical effects in data interpretation.

Findings

Gas-phase abundance ratios are consistent across many objects.

Ice abundance ratios are similar or higher than gas ratios.

Variations in COM ratios suggest chemical and physical influences.

Abstract

Complex organic molecules (COMs) have been detected abundantly at various stages of star formation, particularly in the warm protostellar phase. The progress in gas-phase measurements has been accelerated by the advent of the Atacama Large Millimeter/submillimeter Array and in ice measurements by the James Webb Space Telescope. Particularly, the community has moved from single-source studies of COMs to statistical analyses because of these powerful instruments. In this article, I review surveys that consider COMs in the gas and ice. The two takeaways from this review include; 1. Gas-phase abundance ratios for some COMs show a small difference across many objects and the ice abundance ratios show similar or higher values to the gas, both pointing to the importance of ice chemistry in COM formation, 2. Some COM ratios show larger differences across many objects which could be due to either chemical or physical effects, thus both factors need to be considered when interpreting the data.