astrochemistry

Astrochemistry is the study of the chemical processes that occur in astronomical environments and their role in the evolution of matter in the universe. It bridges astronomy and chemistry to understand which molecules form in space, how they form, and how their abundances change under extreme conditions of temperature, density, and radiation.

The field encompasses a wide range of settings, including the interstellar medium and molecular clouds, star-forming regions, protoplanetary disks, planetary atmospheres, comets, and meteorites. Molecules detected in space range from simple diatomic species to complex organic compounds, identified through spectroscopy across radio, infrared, optical, and ultraviolet wavelengths. Rotational transitions probe cold gas, while vibrational and electronic transitions reveal warmer regions and excited states.

Key chemical processes include gas-phase ion-molecule and neutral-neutral reactions, photochemistry driven by ultraviolet and visible light, cosmic-ray–induced chemistry, and chemistry on dust grain surfaces, where ices and radical reactions alter composition. The interplay between physical conditions and chemical networks shapes molecular abundances and the thermal history of environments.

Methods combine observational astronomy, laboratory experiments that simulate interstellar ices and low-temperature kinetics, and theoretical modeling. Researchers use spectral data, quantum chemical calculations, and chemical networks to predict and interpret molecular abundances in space.

Astrochemistry informs the origins of complex organic molecules and has implications for prebiotic chemistry and the emergence of life in planetary systems. Ongoing work faces uncertainties in reaction rates at low temperatures and in poorly constrained environments, but advances in instrumentation and computation continue to expand the known inventory of spaceborne molecules.