About J2210+57
J2210+57 is an uncommon pulsar. It spins once every 2,057.43 ms and has a dispersion measure of 189.43 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.