[填空题]
Stars located in a certain cluster are tpr;dv81iu4 + j gt)juassumed to be about the same di 39t3)u0:emr dan ijyestance from us. Two such stars have spectra that p:3 ty 9)u3neirej 0mdaeak 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.]
