Q&A: Supernova Remnants and Neutron Stars

Q:
Do neutron stars decay?

A:
The eventual fate of a neutron star depends on its environment. If left to itself, it is possible that the neutrons will convert to free quark's and form a strange quark star, that would be stable until (and if) the quark's decayed into photon and neutrinos over a time of a million trillion trillion years.

The other possibility is that the neutron star could accrete enough material from a companion star or a dense cloud to push it over the stability limit, whereupon it would collapse to form a black hole.