About J2140-2310B
J2140-2310B is an uncommon pulsar. It spins once every 12.986 ms and has a dispersion measure of 25.09 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.