About J0740+6620
J0740+6620 is an epic pulsar. It spins once every 2.886 ms, has a dispersion measure of 14.96 pc cm⁻³ and carries a surface magnetic field around 189,796,933 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.