[填空题]
Stars located in a certaiy.dvo5 87cnmcz*h yu +n bgmkc0/ **grtcluster are assumed to be about the same distance from us. Two s0bkgr/ *ctg *much stars have spectra that peak at $\lambda_1 = 500\ \text{nm}$ and $\lambda_2 = 700\ \text{nm}$, and the ratio of their apparent brightness is $l_1/l_2 = 0.091$. Estimate their relative sizes (give ratio of their diameters). [Hint: use the Stefan-Boltzmann equation, Eq. 14–5.]
