Instability of a Comet Ionopause: Consequences of Collisions and Compressibility

doi:doi:10.1029/JA091iA08p08782

Abstract

Cited By (2)

Abstract

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 91, NO. A8, PP. 8782-8788, 1986
doi:10.1029/JA091iA08p08782

Instability of a Comet Ionopause: Consequences of Collisions and Compressibility

Alexander I. Ershkovich

Raymond and Beverly Sackler Faculty of Exact Sciences, Department of Geophysics and Planetary Sciences, Tel Aviv University, Ramat Aviv, Israel

Dina Prialnik

Raymond and Beverly Sackler Faculty of Exact Sciences, Department of Geophysics and Planetary Sciences, Tel Aviv University, Ramat Aviv, Israel

Aharon Eviatar

Raymond and Beverly Sackler Faculty of Exact Sciences, Department of Geophysics and Planetary Sciences, Tel Aviv University, Ramat Aviv, Israel

We have analyzed the stability of a contact surface located at the ram pressure balance position in a comet coma ionosphere in the presence of collisions between ions and neutrals and finite compressibility. We find that if the surface is taken to be a tangential discontinuity which excludes the interplanetary magnetic field from the ionosphere, this ionopause will be violently unstable to MHD modes. We therefore expect the large-scale magnetic field to permeate the entire coma, even during periods of quiet solar activity. As a result, a stable cometary ionopause may form at a much greater distance from the nucleus.

Received 21 May 1985; accepted 29 January 1986; .

Citation: Ershkovich, A. I., D. Prialnik, and A. Eviatar (1986), Instability of a Comet Ionopause: Consequences of Collisions and Compressibility, J. Geophys. Res., 91(A8), 8782–8788, doi:10.1029/JA091iA08p08782.

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