= Chandrasekhar mass from central polytropic constants
{c}
{title2=$M=(K/(c_3G))^{3/2}(3a_3/(4\pi))^2$}
An ultrarelativistic <degenerate electron gas> has $P=K\rho^{4/3}$, so it forms an index-three <stellar polytrope>. Insert $P_c=c_3GM^2/R^4$ and $\rho_c=3a_3M/(4\pi R^3)$ into that equation of state: the radius cancels, leaving the displayed mass. For fully ionized helium, $n_e=\rho/(2m_p)$ and $K=(3/(2\pi))^{1/3}hc/(16m_p^{4/3})$. This is the ideal limiting <Chandrasekhar mass>, rather than a claim that every ordinary <white dwarf> has that mass.
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