[Space] star radius

[Keysh]

Originally Posted by AlexanderHowl

Pulsar planets are most likely captures (they are too close to have formed at their current radius, and the loss of mass during a supernova would have had any surviving planetary cores migrate outwards rather than inwards). The few planets we have found around white dwarfs are likely captures as well.

A paper from 2016 looked at possible formation mechanisms for pulsar planets. From the astrobites summary of that paper:

Out of the five pulsar planets known, the authors believe that the three planets in the PSR 1257+12 system were formed from the disk of a disrupted star, the planet orbiting PSR J1719-1438 is the core of an evaporated white dwarf, and the planet around PSR B1620-26 was captured along with its white dwarf, with the planet now orbiting both of them as a circumbinary planet.