About J2030+2228
J2030+2228 is an uncommon pulsar. It spins once every 630.513 ms, has a dispersion measure of 71.86 pc cm⁻³ and carries a surface magnetic field around 7.56×10^11 G.
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.