= Ejecta binding energy of an initially uniform core
{title2=$E_{\rm ej}=C(M_{\rm Fe}^{5/3}-M_c^{5/3})$}
For an initial uniform <mass density> $\rho$, integrate the gravitational work of the outer spherical shells from enclosed mass $M_c$ to $M_{\rm Fe}$. Since $r(m)=[3m/(4\pi\rho)]^{1/3}$, the positive unbinding cost is $C(M_{\rm Fe}^{5/3}-M_c^{5/3})$, with $C=(3G/5)(4\pi\rho/3)^{1/3}$. This includes shell–core interactions. It does not equal the final compact object's much greater binding energy. Dissociation, later recombination and overlying stellar layers add separate energy accounting.
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