Gravitational collapse is contraction driven by a system's own gravitational attraction or an enclosing potential. Pressure, angular momentum and other stresses can oppose it. A free-fall timescale measures the dynamical contraction rate when pressure support is removed; gas cooling determines whether thermal support can be removed fast enough.
A pressureless uniform sphere initially at rest collapses under Newtonian gravity in a time depending only on its initial mass density. Solving the radial shell equation gives . It is commonly used as a dynamical-time benchmark for cooling and star formation, with the gravitating density rather than gas density alone when other matter supplies gravity.
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Gravitational collapse is a process that occurs when an astronomical object, such as a star, cloud of gas, or a galaxy, undergoes a significant loss of internal pressure, allowing gravity to overwhelm the forces that hold it up. This leads to a rapid decrease in size and an increase in density as the object contracts under its own gravitational pull. In the context of star formation, gravitational collapse typically begins with a cold, dense region of gas and dust in space known as a molecular cloud.