Q&A: Supernova Remnants and Neutron Stars

Q:
I've read the material at http://chandra.harvard.edu/photo/2002/g541/index.html and am wondering if there is a diameter calculated for the size of the neutron star? the point-like source? Rotating at 7 times per second it wouldn't have to be large, hardly bigger than Earth, to have an equatorial linear velocity of the speed of light, and at any distance, for us to be seeing it at all it would almost have to be certainly at least the size of the Earth? What i'm thinking might explain some of the other phenomenon as well.?

A:
Your statement that an Earth-size star would disintegrate if it rotated as fast as 7 times a second is correct. This was one of the early arguments as to why pulsars had to be neutron stars, which have a diameter of about 20 kilometers. We cannot resolve the size of the neutron star, but infer it from the details of the radiation we observe and theory. In the case of the pulsar in G54.1 the energy output is due to a power generated by its rapidly rotating magnetic field.