About J2140-2310A
J2140-2310A is a rare pulsar. It spins once every 11.019 ms and has a dispersion measure of 25.06 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.