About J1854+0012g
J1854+0012g is a rare pulsar. It spins once every 2.71 ms and has a dispersion measure of 204.1 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.