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A vast assemblage of molecular gas that has more than 10 thousand times the mass of the Sun [18] is called a giant molecular cloud (GMC). GMCs are around 15 to 600 light-years (5 to 200 parsecs) in diameter, with typical masses of 10 thousand to 10 million solar masses. [ 19 ]
At the same time, gravity will attempt to contract the system even further, and will do so on a free-fall time = / /, where is the universal gravitational constant, is the gas density within the region, and = / is the gas number density for mean mass per particle (μ = 3.9 × 10 −24 g is appropriate for molecular hydrogen with 20% helium by ...
As it collapses, a molecular cloud breaks into smaller and smaller pieces in a hierarchical manner, until the fragments reach stellar mass. In each of these fragments, the collapsing gas radiates away the energy gained by the release of gravitational potential energy. As the density increases, the fragments become opaque and are thus less ...
Over time an initial, relatively smooth distribution of matter, after sufficient accretion, may collapse to form pockets of higher density, such as stars or black holes. Star formation involves a gradual gravitational collapse of interstellar medium into clumps of molecular clouds and potential protostars .
A new study proposes that the dinosaurs were killed off due to severe global cooling caused when the Earth passed through a ‘giant molecular cloud.’
A total of as many as 159 distinct clouds have been identified overall, of which various characteristics such as density, size, and mass are known; in addition, there are seven large H II regions, three supernova remnants, 45 T Tauri stars, 18 molecular jets, and as many as 215 infrared radiation sources, coincident with young stellar objects ...
The nebular hypothesis says that the Solar System formed from the gravitational collapse of a fragment of a giant molecular cloud, [10] most likely at the edge of a Wolf-Rayet bubble. [11] The cloud was about 20 parsecs (65 light years) across, [10] while the fragments were roughly 1 parsec (three and a quarter light-years) across. [12]
The free-fall time is the characteristic time that would take a body to collapse under its own gravitational attraction, if no other forces existed to oppose the collapse.. As such, it plays a fundamental role in setting the timescale for a wide variety of astrophysical processes—from star formation to helioseismology to supernovae—in which gravity plays a dominant ro