Interstellar ice

Interstellar ice is frozen material in space, usually mantling microscopic dust grains. Its molecules include water, carbon monoxide, and carbon dioxide, and it supplies raw material for complex chemistry.

Interstellar dust: Microscopic solid particles dispersed between stars, composed mainly of silicates, carbonaceous material, and icy mantles. Dust grains provide the surfaces on which interstellar ice accumulates.
Water ice: Solid H₂O whose molecules form an ordered crystal or disordered amorphous solid, depending on conditions. Water is usually the most abundant component of interstellar ice mantles.
Infrared spectroscopy: A technique that identifies molecular vibrations by measuring absorption or emission of infrared light. Distinct absorption bands reveal molecules frozen in interstellar mantles.
Grain-surface chemistry: Chemical reactions occurring on the surfaces of solid particles in space. Interstellar ice mantles provide the environment for many low-temperature surface reactions.
Interstellar ice spectroscopy: The analysis of infrared absorption and emission features produced by frozen molecules in space. Overlapping spectral bands complicate precise estimates of ice composition and structure.
Molecular cloud: A cold, dense interstellar cloud dominated by molecular gas and dust. Its low temperatures and densities allow gas molecules to freeze onto grains.
Carbon monoxide: A molecule consisting of one carbon atom bonded to one oxygen atom. CO often forms a substantial, volatile layer in cold interstellar mantles.
James Webb Space Telescope: A space observatory designed to observe the universe mainly in infrared wavelengths. Its infrared sensitivity measures ice features in obscured star-forming regions.
Formaldehyde: The simplest aldehyde, with the formula CH₂O. Hydrogenation of frozen CO can produce formaldehyde within icy mantles.
Ice segregation: The separation of mixed ice components into compositionally distinct regions or phases. Laboratory and astronomical evidence tests how mixed mantles reorganize as they warm.

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