About J1954+2923
J1954+2923 is an uncommon pulsar. It spins once every 426.677 ms, has a dispersion measure of 7.93 pc cm⁻³ and carries a surface magnetic field around 2.73×10^10 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.