About J2350+31
J2350+31 is an uncommon pulsar. It spins once every 508.1 ms and has a dispersion measure of 39.14 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.