About J1819-17
J1819-17 is an uncommon pulsar. It spins once every 2,352.135 ms and has a dispersion measure of 67 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.