About J2133-0049E
J2133-0049E is a rare pulsar. It spins once every 3.7 ms and has a dispersion measure of 43.8 pc cm⁻³.
The collapsed core of a star that exploded: about one and a half Suns of matter crushed into a ball the size of a city, held up only by the refusal of neutrons to be squeezed further.