= Global projected virial estimate of a mass-to-light ratio
{title2=$G\Upsilon=\frac{3\int_0^\infty R\mu\sigma_p^2\,dR}{2\int_0^\infty r\lambda L\,dr}$}
For an isolated spherical stellar system in equilibrium with constant <mass-to-light ratio>, the <virial theorem> gives $2K+W=0$. Spherical averaging gives $K=3\pi\Upsilon\int R\mu\sigma_p^2\,dR$, while $W=-4\pi G\Upsilon^2\int r\lambda L\,dr$. Dividing yields the displayed estimator, independent of the radial <velocity-anisotropy parameter>. It requires the full aperture and negligible boundary stress. A radially varying <mass-to-light ratio> or an independent <dark matter halo> prevents interpreting this expression as a general reconstruction of the mass profile.
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