Self-Gravitation

Abstract

For certain dusty plasmas, containing rather heavy charged grains, is was hypothesized that the intergrain gravitational force could become of the order of the intergrain electrostatic force, and this has prompted a revival of the interest in Jeans instabilities and self-gravitational effects, reconsidered in a novel context. As I had the occasion of pointing out in Chapter 3, cosmic dust is a well-known and common constituent of the interstellar medium. It may be charged or neutral depending on the nearby sources of radiation like stars and/or the presence of charged particles. Such cosmic clouds of dust can be very large with widely varying grain diameters, and, in the main, it is these dust clouds that I shall keep in mind here. Before we can go on and address the issue of how charged dust affects the stability or instability, however, I have to recall some notions from neutral gases and in particular, the ambiguities connected with the proper description of gravitational phenomena in such systems.