Building Molecular Complexity: a Balancing Act
In the interstellar medium (ISM), a large amount of matter is locked up in icy layers on top of dust grains formed from the fragments of dying stars. Though these ices exist in very cold regions of space, they act as chemical factories for producing many of the complex organic molecules (COMs) that have been observed in astronomical measurements. The molecular-level pathways that occur in these icy grains is thus a crucial element in accurately predicting the chemical evolution of stellar and planetary systems.
The story of building molecular complexity in interstellar ices is one of balance between constructive and destructive processes. Numerous laboratory studies have shown that we can form many COMs in ices by energetic processing — with, for example, vacuum-ultraviolet (VUV) photons — which leads to dissociation of small molecules to form reactive fragments. These fragments then initiate chain reactions that can produce chains of more atoms than were present in the starting material, and may even lead to the formation of biomolecular precursors in interstellar space.
PSI-COM: Finding the Astronomical Settings in which COMs Thrive
My Marie Curie project — Photo-Stability of Ice-bound Complex Organic Molecules (PSI-COM) — aims to put this balance into greater focus by characterizing the stability of astronomically-relevant COMs with respect to the harsh conditions that often lead to their formation. By controlling factors that influence the photostability, we can determine conditions which may be particularly favorable to allowing COMs to survive into later stages of planet formation. This project, hosted by the Leiden Observatory, consists of three work packages (WPs), all of which involve laboratory experiments performed predominantly in the Lab for Astrophysics in Leiden. These experiments will be informed by observations, and the resultant data will be interpreted with the assistance of theoretical calculations, representing an interdisciplinary effort to improve our understanding of how molecules form in space.