In physics, the Jeans instability causes the collapse of interstellar gas clouds and subsequent star formation. It occurs when the internal gas pressure is not strong enough to prevent gravitational collapse of a region filled with matter. For stability, the cloud must be in hydrostatic equilibrium, which in case of a spherical cloud translates to:
where is the enclosed mass, is the pressure, is the density of the gas at, is the gravitational constant and is the radius. The equilibrium is stable if small perturbations are damped and unstable if they are amplified. In general, the cloud is unstable if it is either very massive at a given temperature or very cool at a given mass for gravity to overcome the gas pressure.
Other articles related to "jeans length, jeans, length":
... Jeans' length is the critical radius of a cloud (typically a cloud of interstellar dust) where thermal energy, which causes the cloud to expand, is counteracted by gravity ... It is named after the British astronomer Sir James Jeans, who concerned himself with the stability of spherical nebula in the early 1900s ... The formula for Jeans Length is where is Boltzmann's constant, is the temperature of the cloud, is the radius of the cloud, is the mass per particle in the cloud, is the Gravitational Constant and is the cloud's ...
... Jeans instability can also give rise to fragmentation in certain conditions ... analysis For adiabatic processes, For an ideal gas, Polytropic equation of state, Jeans mass, Thus, If adiabatic index, Jeans mass increases with increasing density while ... gravitational collapse density always increases, thus in the second case Jeans mass will decrease during collapse allowing smaller overdense regions to collapse ...
... The Jeans mass is named after the British physicist Sir James Jeans, who considered the process of gravitational collapse within a gaseous cloud ... The approximate value of the Jeans mass may be derived through a simple physical argument ... The condition for gravitational collapse is therefore The resultant Jeans length is approximately This length scale is known as the Jeans length ...
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—Ralph Waldo Emerson (18031882)
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—David Elkind (20th century)