Self-gravitational magnetosonic modes in dusty plasmas with quasi-inertialess plasma constituents

Self-gravitation could become important in dusty plasmas, due to the presen ce of very heavy charged dust grains, and hence could modify traditional Je ans collapse criteria known from neutral gases. Perpendicular, low-frequenc y magnetosonic modes can play a role in resisting gravitational collapse ac ross the magnetic field. By treating the lighter plasma species as effectiv ely inertialess, a unified dispersion law is obtained for Alfven-Jeans mode s, valid at all frequencies smaller than the ordinary ion gyrofrequency. It s possible relevance for interstellar space is discussed, although estimate s are only indicative because of the lack of reliable data. Nevertheless, t his clearly points to an important stabilizing role for the interstellar ma gnetic field in the perpendicular direction if all the dust is charged. (C) 1999 American Institute of Physics. [S1070-664X(99)03901-4].