As the Mach number of the upstream flow becomes increasingly hypersonic, the equations for the pressure, density, and temperature after the oblique shock wave reach a mathematical limit.  The pressure and density ratios can then be expressed as:
For a perfect atmospheric gas approximation using γ = 1.4, the hypersonic limit for the density ratio is 6.  However, hypersonic post-shock dissociation of O and N into O and N lowers γ, allowing for higher density ratios in nature.  The hypersonic temperature ratio is: