The correct answer is: They cause nuclear fusion inside the inner core of planets.
Stars with about eight to 20 solar masses become neutron stars when they die. When infalling matter from the imploding star's outer layers reaches this neutron core, it bounces back and produced a stellar explosion called a supernova. But, The supernova explosion should destroy any pre-existing planets, and so the neutron star needs to capture more raw materials to form its new companions.