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An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies. But differently, an interstellar cloud is a denser-than-average region of the interstellar medium , the matter and radiation that exists in the space between the star systems in a galaxy.
Stars form by gravitational collapse of interstellar gas clouds. As the collapse increases the density, radiative energy loss decreases due to increased opacity. This raises the temperature of the cloud which prevents further collapse, and a hydrostatic equilibrium is established. Gas continues to fall towards the core in a rotating disk.
The interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space.
Molecular clouds typically have interstellar medium densities of 10 to 30 cm −3, and constitute approximately 50% of the total interstellar gas in a galaxy. [11] Most of the gas is found in a molecular state. The visual boundaries of a molecular cloud is not where the cloud effectively ends, but where molecular gas changes to atomic gas in a ...
An interstellar cloud of gas will remain in hydrostatic equilibrium as long as the kinetic energy of the gas pressure is in balance with the potential energy of the internal gravitational force. Mathematically this is expressed using the virial theorem , which states that to maintain equilibrium, the gravitational potential energy must equal ...
In the low-density (H atoms per ) diffuse interstellar medium, dust particles up to micron size couple with gas clouds within a frictional scale of less than 1 pc. Within the denser, colder interstellar medium found in molecular clouds ( n H = 10 8 − 10 12 m − 3 {\displaystyle {10^{8}-10^{12}m^{-3}}} ), the growth of grains occurs through ...
What she saw was a Kelvin-Helmholtz wave cloud, named after Hermann von Helmholtz, who discovered the atmospheric instability that leads to this phenomenon. These waves in the s Waves in the sky ...
The extremely low density of the interstellar medium is not conducive to the formation of molecules, making conventional gas-phase reactions between neutral species (atoms or molecules) inefficient. Many regions also have very low temperatures (typically 10 kelvin inside a molecular cloud), further reducing the reaction rates, or high ...