Electric potential of nonspherical interstellar grains

The equilibrium electric potential of graphite and silicate spheres and infinite cylinders is calculated for the conditions characteristic of diffuse clouds, the interstellar medium, and H II regions around hot stars. Collisions of the dust grains with electrons and ions are taken into account together with photoelectric emission. The dependence of the potential on the grain parameters (shape, size, chemical composition, and velocity) and also on the gas parameters is briefly discussed. It is found that the potential of nonspherical grains can differ appreciably from that of spherical ones only in diffuse clouds (however, their ratio is usually less than 10).