About J1842+0257
J1842+0257 is an uncommon pulsar. It spins once every 3,088.256 ms, has a dispersion measure of 146 pc cm⁻³ and carries a surface magnetic field around 9.67×10^12 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.