About J1925-16
J1925-16 is an uncommon pulsar. It spins once every 3,885.8 ms and has a dispersion measure of 88 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.