About J1928+1902g
J1928+1902g is a rare pulsar. It spins once every 5.8 ms and has a dispersion measure of 28.9 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.