Ultra-low-frequency electrostatic waves in a self-gravitating magnetized and inhomogeneous dusty plasma

Obliquely propagating ultra-low-frequency electrostatic waves in a self-gravitating uniformly magnetized and inhomogeneous dusty plasma are investigated using the gyro-kinetic theory for the dynamics of the charged dust grains, ions and electrons. The modes are found to be unstable under certain conditions. It is noticed that when the perpendicular phase velocity of the mode is higher than the dust-drift velocity VDd, (ω/k↑ ≫ VDd), the modified dust-acoustic mode due to gravity suffers Jeans instability and when ω/k↑ < VDd, the modified dust-drift mode suffers universal instability which is due to the diamagnetic drift of dust particles. The implications of this result for some space and astrophysical situations are also indicated. © 1999 Elsevier Science Ltd. All rights reserved.