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hydrostatic equilibriumA state of equilibrium in which the inwardly directed gravitational force in a star just balances the outwardly directed gas and radiation pressure. The star is thus held together but supported against collapse. The equation of hydrostatic equilibrium is given at stellar structure.
hydrostatic equilibrium[‚hī·drə′stad·ik ‚ē·kwə′lib·rē·əm]
The state of a fluid whose surfaces of constant mass (or density) coincide and are horizontal throughout; complete balance exists between the force of gravity and the pressure force; the relation between the pressure and the geometic height is given by the hydrostatic equation.