About J1904+0800
J1904+0800 is an uncommon pulsar. It spins once every 263.345 ms, has a dispersion measure of 438.8 pc cm⁻³ and carries a surface magnetic field around 2.16×10^12 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.