About J1812-15
J1812-15 is an uncommon pulsar. It spins once every 1,014.529 ms and has a dispersion measure of 431 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.