About J1246+2253
J1246+2253 is an uncommon pulsar. It spins once every 473.871 ms, has a dispersion measure of 17.79 pc cm⁻³ and carries a surface magnetic field around 2.08×10^11 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.