Detachment and instability of cometotail

Abstract

The two types of comet tails (ion and dust) present different morphological structures whose origin has been reviewed in this paper. The change of magnetic field direction during sector boundary crossings is known to be the source of blob formation in cometotail regions. In this paper it is shown that in the absence of sector boundary changes, the predominant velocity shear on the lower and upper side of the cometotail may result into the instability and blob formation. The growth rate of the instability for different conditions of plasma tail has been studied. It is shown that the onset of instability depends on the shape and thickness of the ion cometotail. In the extended thick ion cometotails, the onset of Kelvin-Helmholtz (K-H) instability is less likely whereas in the thin and extended tail, the K-H instability mechanism is more effective in structuring the ion cometotails into blobs. © 1993.