[填空题]
Stars located in a certain clusz;f2ct7d(*d szdo /f ster are assumed to be about the same 8yxh)j6z3lixdistance from us. Two such stars have spectra l6xj3z8yxi)hthat 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.]
