Neutron Stars Despite the fact a neutron star is only about 13 miles (20km) in diameter it is about 1.5 times more massive than the sun. (Illustration: NASA/CXC/M.Weiss) Larger version: http://chandra.si.edu/resources/illustrations/infographics.html Related Link: http://chandra.si.edu/xray_sources/neutron_stars.html
Pulsar - A pulsar (pulsating star) is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. Neutron stars are very dense, and have short, regular rotational periods. This produces a very precise interval, between pulses that range from roughly milliseconds to seconds for an individual pulsar. Certain types of pulsars rival atomic clocks in their accuracy in keeping time.