[填空题]
Astronomers using the Hubble Space Telescoew4 6wzjmww*a ma 2)l135al adpe deduced the presence of an extg j vfunze 28wuop5;t, j20uhy3u0mn;remely massive core in the distant galaxy M87, so dense that it could be a black hole (from which no light escapes). They did this by measuring the speed of gas clouds orbiting the core to be u;g8e0ujuw,; y f p2o zn3j2mhnvtu05 780 $\mathrm{~km} / \mathrm{s}$ at a distance of 60 lightyears $ \left(5.7 \times 10^{17} \mathrm{~m}\right)$ from the core. Deduce the mass of the core, and compare it to the mass of our Sun. v = $\times 10^{39}$solar masses = $\times 10^9$
