About J2030+3944g
J2030+3944g is an uncommon pulsar. It spins once every 306.18 ms and has a dispersion measure of 937.4 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.