The Kelvin-Helmholtz instability at Venus: What is the unstable boundary?

Тип публикации: статья из журнала

Год издания: 2011

Идентификатор DOI: 10.1016/j.icarus.2011.09.012

Ключевые слова: Magnetospheres, Solar wind, Venus, Magnetospheres, Solar wind, Venus

Аннотация: The Kelvin-Helmholtz instability gained scientific attention after observations at Venus by the spacecraft Pioneer Venus Orbiter gave rise to speculations that the instability contributes to the loss of planetary ions through the formation of plasma clouds. Since then, a handful of studies were devoted to the Kelvin-Helmholtz instability at the ionopause and its implications for Venus. The aim of this study is to investigate the stability of the two instability-relevant boundary layers around Venus: the induced magnetopause and the ionopause. We solve the 2D magnetohydrodynamic equations with the total variation diminishing Lax-Friedrichs algorithm and perform simulation runs with different initial conditions representing the situation at the boundary layers around Venus. Our results show that the Kelvin-Helmholtz instability does not seem to be able to reach its nonlinear vortex phase at the ionopause due to the very effective stabilizing effect of a large density jump across this boundary layer. This seems also to be true for the induced magnetopause for low solar activity. During high solar activity, however, there could occur conditions at the induced magnetopause which are in favour of the nonlinear evolution of the instability. For this situation, we estimated roughly a growth rate for planetary oxygen ions of about 7.6 x 10(25) s(-1), which should be regarded as an upper limit for loss due to the Kelvin-Helmholtz instability. (C) 2011 Elsevier Inc. All rights reserved.

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Издание

Журнал: ICARUS

Выпуск журнала: Vol. 216, Is. 2

Номера страниц: 476-484

ISSN журнала: 00191035

Место издания: SAN DIEGO

Издатель: ACADEMIC PRESS INC ELSEVIER SCIENCE

Авторы

  • Mostl U.V. (Institute of Physics,Karl-Franzens-University Graz)
  • Zellinger M. (Institute of Physics,Karl-Franzens-University Graz)
  • Lammer H. (Space Research Institute,Austrian Academy of Sciences)
  • Groller H. (Space Research Institute,Austrian Academy of Sciences)
  • Biernat H.K. (Institute of Physics,Karl-Franzens-University Graz)
  • Korovinskiy D. (Space Research Institute,Austrian Academy of Sciences)
  • Erkaev N.V. (Siberian Federal University)

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