About J1354+2454
J1354+2454 is an uncommon pulsar. It spins once every 6,270 ms and has a dispersion measure of 20 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.