[填空题]
Suppose a star the size of ourev:c mtw (yx01e( naw/ Sun, but with mass 8.7vfybf*ycj.p(( m g9y 0 times as great, were rotating at a speed of 1.0 revolution every 12 days. If it were to jym (y bvp.(*gff yc97undergo 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. $\times10^{9 }$ $rev/day$