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Forms on the surface of dust grains in cold molecular clouds. It catalyzes chemical reactions and contributes to the formation of planets by providing material for planetesimals in protoplanetary disks.

Neutral atomic hydrogen that emits at a characteristic wavelength of 21 cm, important for the cooling of gas in the interstellar medium and as a precursor to molecular hydrogen formation.

A non-luminous and non-baryonic component that exerts gravitational forces, influencing the structure and evolution of galaxies. It indirectly affects star formation by contributing to galactic potentials.

A chemical element found in interstellar dust, often bonded with silicates or other elements. It is a key component in the composition of interstellar dust grains.

Second most abundant molecular component after H2 in molecular clouds. It is used as a tracer for molecular hydrogen due to its strong emission lines and relative ease of detection.

The condition under which interstellar gas clouds become gravitationally unstable, leading to collapse and star formation, described by the Jeans Criterion: $\rho > \frac{J^2}{\pi G L^4}$, where $\rho$ is the density, $G$ is the gravitational constant, $L$ the characteristic size, and $J$ the Jeans mass.

Mineral compounds composed of silicon and oxygen. Found in interstellar dust, they contribute to the dust's optical properties and to the solid component of planetesimals.

A vital element for forming ammonia (NH3) and other nitrogenated molecules in interstellar space. They play an important role in the chemistry of the interstellar medium and prebiotic molecules.

Second most abundant element in the universe, often found in the interstellar medium. It does not form molecules easily due to its inertness but contributes to the mass of interstellar clouds.

High-energy particles that traverse space and can ionize atoms and molecules in clouds, influencing the chemistry and physical processes necessary for star formation.

A noble gas that is found in its ionized form in planetary nebulae and H II regions. Its spectral lines serve as important diagnostics in astrophysical processes.

The study of the magnetic properties and behavior of ionized gases in astrophysics, critical for understanding the dynamics of the interstellar medium, star formation, and the shaping of protoplanetary disks.

The early stage of star formation when a region within a molecular cloud collapses under gravity and begins to heat up before nuclear fusion starts.

Found in the cores of massive stars and dispersed into the interstellar medium by supernovae. Iron in dust grains is crucial for the dust's ability to absorb ultraviolet radiation.

The most abundant molecule found in molecular clouds where star formation occurs. It plays a vital role as the primary constituent of these clouds, contributing to cloud collapse under gravity.

Composed of tiny solid particles that block and scatter light, aiding the cooling of molecular clouds and the formation of H2 on their surfaces, which is crucial for star formation.

Rotating disks of dense gas and dust surrounding a new star, from which planets ultimately form through accretion and collision processes.

Complex organic molecules that dominate the infrared spectrum with their emissions. They contribute to the heating of interstellar clouds by absorbing ultraviolet light.

Gas consisting of ions and electrons, created by the ionization of neutral gas. It is found in H II regions around hot stars and affects the propagation of electromagnetic signals.