Roche-lobe period-mass relation for a linear donor radius law
= Roche-lobe period-mass relation for a linear donor radius law
{c}
{title2=$P/P_0=M_d/M_\odot$}
For contact with $R_d/R_\odot=M_d/M_\odot$ and $R_L/a=f(M_d/M)^{1/3}$, <Kepler's third law> gives $P_0=2\pi\sqrt{R_\odot^3/(f^3GM_\odot)}$. The total binary mass cancels. The linear period relation depends on that particular equilibrium radius sequence; a donor with a different <stellar radius response exponent> follows a different mass-period relation.