About J1855+0422
J1855+0422 is an uncommon pulsar. It spins once every 1,678.106 ms, has a dispersion measure of 455.6 pc cm⁻³ and carries a surface magnetic field around 1.26×10^12 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.