# A Rotating Pulsar

1. Oct 26, 2005

### Skomatth

A pulsar is a rapidly rotating neutron star that emits a radio beam the way a lighthouse emits a light beam. We receive a radio pulse for each rotation of the star. The period T of rotation is found by measuring the time between pulses. The pulsar in the Crab nebula has a period of rotation of T=.033s that is increasing at the rate of 1.26 x 10^-5 s/y

a)What is the pulsar's angular acceleration?
I know that T=2pi/w when omega is constant. Does it make sense to that that T(t)=2pi/w(t) ? If this is correct then I can get the answer, but even if it is correct I'm not sure why it works.

2. Oct 26, 2005

### Danger

I can't do the math. Just remember that the beams are emitted from the magnetic poles of the star, so you can expect that once in a while the orientation will be such that we receive two pulses per revolution. I don't know if any currently known ones are like that, though.

3. Oct 27, 2005

### Skomatth

Judging by the context of the problem this is irrelevant.

4. Oct 27, 2005

### Staff: Mentor

Makes sense to me. Note that the rate of change of the period is so slow that for all practical purposes the angular speed hardly changes during one revolution.