Astrophysics (Index)About

Jeans parameter

(λ, Jeans escape parameter, escape parameter)
(ratio measuring a tendency of an atmosphere to escape)

The Jeans parameter is a measure of an atmosphere's gas particles' tendency to escape (atmospheric escape) through a thermal escape mechanism (Jeans escape or hydrodynamic escape). It is a ratio of the gravitational potential energy of the particles to their kinetic energy. In a (virtually) spherically-symmetric situation, it is a function of distance from the center of the body. The smaller the Jeans parameter, the more likely the escape, and thresholds have been devised to indicate whether such escape is a significant possibility.

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