Noun
Hayashi limit (plural Hayashi limits)
(astrophysics) A theoretical maximum radius of a star of given mass; the radius at which the inward force of gravity exactly balances the outward pressure of the gas of the star.
When a star is fully within hydrostatic equilibrium—a condition where the inward force of gravity is matched by the outward pressure of the gas—the star can not exceed the radius defined by the Hayashi limit.