Hydrostatic equilibrium of stars without electroneutrality constraint
The general solution of hydrostatic equilibrium equations for a two-component fluid of ions and electrons without a local electroneutrality constraint is found in the framework of Newtonian gravity theory. In agreement with the Poincaré theorem on analyticity and in the context of Dyson's argument, the general solution is demonstrated to possess a fixed (essential) singularity in the gravitational constant $G$ at $ G = 0 $. The regular component of the general solution can be determined by perturbation theory in $G$ starting from a locally neutral solution. The non-perturbative component obtained using the method of Wentzel, Kramers and Brillouin is exponentially small in the inner layers of the star and grows rapidly in the outward direction. Near the surface of the star, both components are comparable in magnitude, and their non-linear interplay determines the properties of an electro- or ionosphere. The stellar charge varies within the limits of $- 0.1 $ to $150$ C per solar mass. The properties of electro- and ionospheres are exponentially sensitive to variations of the fluid densities in the central regions of the star. The general solutions of two exactly solvable stellar models without a local electroneutrality constraint are also presented.