Suppose the a star of mass 2M⊙ and radius R = 1.5R⊙, with a rotation period similar to the Sun, collapses to a neutron star of radius 11km, whilst losing 25% of its mass. Calculate the resulting rotation period of the neutron star. Give your answer in units of both seconds. Briefly describe how this compares with the observed properties of pulsars. State what other property is required to explain the observed emission from pulsars. The following may be useful: On the Sun’s equator sunspots typically take 26 days to make one full rotation. The angular momentum (a conserved quantity) of a rotating body is given by Iω, where I is the moment of inertia and ω is the angular frequency. A uniform sphere, mass M and radius R, has a moment of inertia I = 2/5MR2.

Suppose the a star of mass 2M⊙ and radius R = 1.5R⊙, with a rotation period similar to the Sun,
collapses to a neutron star of radius 11km, whilst losing 25% of its mass.

Calculate the resulting rotation period of the neutron star. Give your answer in units of both
seconds.

Briefly describe how this compares with the observed properties of pulsars. State what other
property is required to explain the observed emission from pulsars.

The following may be useful: On the Sun’s equator sunspots typically take 26 days to make one
full rotation. The angular momentum (a conserved quantity) of a rotating body is given by Iω,
where I is the moment of inertia and ω is the angular frequency. A uniform sphere, mass M and
radius R, has a moment of inertia I = 2/5MR².