All stars have to be electrically charge neutral, since the gravitational force is about 1036 times weaker than the electromagnetic force. Calculate what is the maximum ratio of charged particle per nucleon Z/A you can have in a star, so it does not expel a proton from the surface. In other words, the gravitational force between a proton and the remaining star must be larger than the Coulomb's force. Use that the gravitational mass of the star M is less than the baryonic mass mpA.

All stars have to be electrically charge neutral, since the gravitational force is about 1036 times weaker than the electromagnetic force. Calculate what is the maximum ratio of charged particle per nucleon Z/A you can have in a star, so it does not expel a proton from the surface. In other words, the gravitational force between a proton and the remaining star must be larger than the Coulomb's force. Use that the gravitational mass of the star M is less than the baryonic mass mpA.