About J1936+18
J1936+18 is an uncommon pulsar. It spins once every 58.345 ms and has a dispersion measure of 125.9 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.