About J2312+6931
J2312+6931 is an uncommon pulsar. It spins once every 813.375 ms, has a dispersion measure of 71.6 pc cm⁻³ and carries a surface magnetic field around 7.24×10^11 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.