Can a Neutron Star become charged?

If you keep adding electrons or protons to a Neutron star, what would happen? Are there decay processes that convert them to neutrons in the absence of the oppositely charged particle?

• The net charge of almost all astronomical objects is zero. Your question is equivalent to asking "what happens if we keep adding electrons or protons to any astronomical body"? As you'd expect, the electric charge would change. Oct 18, 2017 at 21:05
• @SirCumference But aren't electrons and protons unstable on a neutron star? Also since black holes can become charged, I was just wonder if the same thing happened to neutron stars. Oct 18, 2017 at 21:09
• @A.C.A.C. The process where electrons and protons become neutrons inside a neutron star doesn't change it's charge. The outer rim is still protons, neutrons and electrons and it's charge is a sum of the charge of it's particles. A black hole is different. Apr 11, 2018 at 20:27

Charge is a conserved quantity. If you add a net charge to an object, then it becomes charged.

The pressures are so great in a neutron star that most of the electrons combine with protons and become neutrons. A statistical equilibrium is set up in which neutrons, because they are unstable, decay into electrons and protons while some electron proton pairs form neutrons. For typical neutron star temperature/pressures, at any one time about 1/7 of the nucleons are protons (with an equal number of electrons) and 6/7 are neutrons. If there were more electrons than protons, then the excess of electrons would persist since they would not have enough partners to combine with. Of course, this net charge would attract protons and other positive ions from nearby space and this would reduce the neutron star's charge. So, if you added electrons, you would change the charge of the neutron star, but the net charge would decay over time as positive particles are pulled in from space.

• I think your answer can be improved, especially the last phrase. So what are you proposing, net charge yes/no? Oct 28, 2017 at 14:41