[填空题]
Suppose a star the size of5lu, )pmzj :i.h g:uuf our Sun, but s qh,lck2/vlkw0 :rr o(/1c ulwith mass 8.0 times as great, were rotating at a speed of 1.0 revolution every 12 days. If it were to undergo 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 mom1h(0cs urvc/klr/:lkq2lwo , entum. $\times10^{9 }$ $rev/day$