About J2004+3137
J2004+3137 is an uncommon pulsar. It spins once every 2,111.265 ms, has a dispersion measure of 234.82 pc cm⁻³ and carries a surface magnetic field around 1.27×10^13 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.