[填空题]
Astronomers have recentys6)t *zq0eskv3jb)e )ef+y xlp wu6mo/a7f9kow+b xfzi0uvm-:h- l 3 y measured the rotation of gas around what might be a supermassive black hole of about 2 billion solar masses at the center of a galaxy. If the radius from the galactic center to the gas clouds is 60 light-years, what Doplpobz6 a-3f i hkuofwx+wv u7-/:m9m0pler shift $\Delta\lambda/\lambda_0$ do you estimate they saw? z$\approx $ $ \times 10^{-3}$
