[填空题]
Suppose a star the size of og)ti,;lwr*os1vp key9 es35o ur Sun, but with mass 8.9)1t* syo ec3+ ackkrd0 times as great, were rotating at a speed of 1.0 revolution every 12 days. If it were to uno3*r)dkse kac + y91tcdergo gravitational collapse to a neutron star of radius 11 km, losing three-quarters of its mass in the process, what would its rotation speed be? Assume that the star is a uniform sphere at all times, and that the lost mass carries off no angular momentum. $\times10^{9 }$ $rev/day$