The evolution of a star depends on its size. If a star is sufficiently large, the gravity forces holding it together may be large enough to collapse it into a very dense object composed mostly of neutrons. The density of such a neutron star is about 1014 times that of the earth. Suppose that a star initially had a radius about that of our sun, 7 × 108 km, and that it rotated once every 26 days, as our sun does. What would be the period of rotation (the time for 1 rev) if the star collapsed to a radius of 15 km?

The evolution of a star depends on its size. If a star is sufficiently large, the gravity forces holding it together may be large enough to collapse it into a very dense object composed mostly of neutrons. The density of such a neutron star is about 1014 times that of the earth. Suppose that a star initially had a radius about that of our sun, 7 × 108 km, and that it rotated once every 26 days, as our sun does. What would be the period of rotation (the time for 1 rev) if the star collapsed to a radius of 15 km?