2R_{A} + 2R_{B} = (t_{4} − t_{1}) ∗ (v_{A} + v_{B}) 2R_{A} − 2R_{B} = (t_{3} − t_{2}) ∗ (v_{A} + v_{B}) circumference C = v ∗ P = 2πr

\frac{v_{A}}{v_{B}} = \frac{m_{B}}{m_{A}}

\begin{aligned}B_{tot} & = 4πR_{A}^{2}σT_{A}^{4} + 4πR_{B}^{2}σT_{B}^{4} \\ B_{sec} & = 4πR_{A}^{2}σT_{A}^{4} \\ B_{pri} & = 4π(R_{A}^{2} − R_{B}^{2})σT_{A}^{4} + 4πR_{B}^{2}σT_{B}^{4} \end{aligned}

B_{tot} − B_{pri} = 4πσR_{B}^{2}T_{A}^{4} B_{tot} − B_{sec} = 4πσR_{B}^{2}T_{B}^{4}

\frac{B_{tot} − B_{pri}}{B_{tot} − B_{sec}} = (\frac{T_{A}}{T_{B}} )^{4}

L = 4πR_{A}^{2}σT_{A}^{4} + 4πR_{B}^{2}σT_{B}^{4}