Particles {interstellar dust}| are between stars. Interstellar dust is 1% of interstellar matter, which is 99% hydrogen and helium. 10% is 0.005-nm carbon and hydrogen particles. 80% is 0.35-nm mostly iron, carbon, and silicate particles with organic mantles. Mantles can be simple organic molecules, like formaldehyde, or complex organics {polycyclic aromatic hydrocarbons} (PAH), caused by different ultraviolet-radiation levels. 10% is 0.002-nm polycyclic aromatic hydrocarbons.
source
Most interstellar dust came from red-giant nova atmospheres.
gas
In dense clouds, which are colder, water and ammonia stick to dust. Otherwise, radiation evaporates gas from surfaces.
comets
Comets are dust grains stuck together.
Physical Sciences>Astronomy>Galaxy>Parts
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Date Modified: 2022.0224