Eddington quartic relation
= Eddington quartic relation
{c}
For a chemically uniform $n=3$ gas-plus-radiation polytrope with constant gas-pressure fraction $\beta$, the mass obeys
$$
\frac{1-\beta}{\beta^4}\propto\mu^4M^2.
$$
It follows from the $n=3$ mass scaling $M\propto K^{3/2}$ and the equation of state.