If a star is formed such that some region in its deep interior has large ∇ ∇ − − ∇ ∇ a d i a b a t i c > 0 large convective fluxes with velocities v c o n v e c t i v e ≈ ≈ ( ∇ ∇ − − ∇ ∇ a d i a b a t i c ) / 2 . The convective fluxes of energy cooldown the interior rapidly until ∇ ∇ = ∇ ∇ a d i a b a t i c and the star has moved to the Hayashi limit. In fact, it can be shown from the mixing length model that even a small excess can transport energy from the deep interior to the surface by convective fluxes. This will happen within the short timescale for the adjustment of convection which is still larger than timescales for non-equilibrium processes in the star such as hydrodynamic adjustment associated with the thermal time scale. Hence, the limit between an “allowed” stable region (left) and a “forbidden” unstable region (right) for stars of given M and composition that are in hydrostatic equilibrium and have a fully adjusted convection is the Hayashi limit.