Does the Streaming Instability Exist within the Terminal Velocity Approximation?

Abstract Terminal velocity approximation is appropriate to study the dynamics of a gas–dust mixture with solids tightly coupled gas. This work reconsiders its compatibility physical processes giving rise resonant streaming instability in low-dust-density limit. It shown that linearized equations have been commonly used within terminal actually exceed accuracy this approximation. For reason, corresponding dispersion equation recovers long-wavelength branch caused by stationary azimuthal drift dust. However, latter must remain beyond definition. The refined for does not lead instability. additionally elucidates responsible