[填空题]
Two stars 15 light-years away are barel93w 4u*ezr pd5okn3zst hbwuf5q , b*/y resolved 4kclri g eyg6wbdn 3l8 -.o,+qby a 55-$cm$ (mirror diameter) telescope. How far apart are the stars? Assume $\lambda=550\mathrm{~nm.}$ and that the resolution is limited by diffraction. $ \times10^{11 }\;m$
