Gravitational equilibrium and the mass limit for dust clouds

Abstract

We show the existence of a new class of astrophysical objects where the self-gravity of the dust is balanced by the force arising from shielded electric fields on the charged dust. The problem of equilibrium dust clouds is formulated in terms of an equation of hydrostatic force balance together with an equation of state. Because of the dust charge reduction at high dust density, the adiabatic index reduces from two to zero. This gives rise to a mass limit M_AS for the maximum dust mass that can be supported against gravitational collapse by these fields. If the total mass M_D of the dust in the interstellar cloud exceeds M_AS, the dust collapses, while in the case M_D < M_AS, equilibrium may be achieved. The physics of the mass limit is similar to the Chandrasekhar's mass limit for compact objects, such as white dwarfs and neutron stars.