Moment of inertia fraction of neutrons enclosed in a spherical shell extending from the radius at which the neutron drip starts to the radius corresponding to a certain baryon number density. Baryon density corresponding to the internal boundary of the shell is given in units of n₀ (nuclear saturation). Vertical line marks the core-crust transition at 0.45n₀. Horizontal line represent x₂ and x₁ + x₂ = 1 − x_p without (solid lines: ) and with strong entrainment in the crust (dashed lines: ). We used the SLy4 equation of state and four reference masses: 1, 1.4, 1.8, and 2 M_⊙. The inset is a zoomed-in image of the outermost regions of the core.