Photochemistry of interstellar ice forming Complex Organic Molecules

TL;DR

This review discusses how photochemistry and thermal processes in interstellar ice lead to the formation of complex organic molecules, which are relevant for astrobiology and the origin of life.

Contribution

It synthesizes current laboratory and observational knowledge on ice photochemistry and thermal processing in space environments.

Findings

Interstellar ice contains simple species like water and other molecules.

Photochemistry in ice leads to complex organic molecules formation.

COMs found in comets and asteroids may have contributed to prebiotic chemistry on Earth.

Abstract

Astrochemistry is a well-established multidisciplinary field devoted to study molecules in space. While most astrochemists are oriented to observe molecules in the gas phase and reproduce their abundances by modeling the physical conditions of the medium, the microscopic dust particles wandering in the interstellar medium deserve the attention of a smaller community. Radiation and thermally-driven processes taking place in the bare dust, and particularly in dust particles covered by ice mantles, are mimicked in the laboratory. In addition to water, interstellar ice contains other simple species. In this Review we present our current knowledge on ice photochemistry and thermal processing that ultimately leads to formation of complex organic molecules (COMs). Numerous COMs are of astrobiological interest and match those present in comets and asteroids. Upon impact of these minor bodies, water and COMs were delivered to the earth and might have intervened in the first prebiotic reactions.