[P-EM10_29PM1] Wave, Turbulence, Reconnection, and Energetic Particles in Solar, Space and Laboratory

★ [PEM10-04] Instabilities and turbulence near the heliopause

*POGORELOV Nikolai¹、BOROVIKOV Sergey²、ZANK Gary¹、ZHANG Ming³ (1.Department of Space Science, University of Alabama in Huntsville、2.CSPAR, University of Alabama in Huntsville、3.Department of Physics and Space Sciences, Florida Institute of Technology)

キーワード：ISM: kinematics and dynamics, ISM: magnetic fields, solar wind, Sun: heliosphere, turbulence

Recent observations from the Voyager 1 spacecraft show that it is sampling the local interstellar medium (LISM). This is quite surprising because no realistic, steady-state model of the solar wind (SW) interaction with the LISM gives the inner heliosheath width as narrow as 30. This includes such models that assume a strong redistribution of the ion energy to the tails in the pickup ion distribution function. We show that the heliopause (HP), which separates the SW from the LISM, is not a smooth tangential discontinuity, but rather a surface subject to Rayleigh-Taylor-type instabilities which can result in the LISM material penetration deep inside the SW. We also show that the HP flanks are always subject to a Kelvin-Helmholtz instability. The instabilities are considerably suppressed near the HP nose by the heliospheric magnetic field in steady-state models, but reveal themselves in the presence of solar cycle effects. We argue that Voyager 1 may be in one of such instability regions and therefore observing plasma densities much higher than those in the pristine SW. These results may be an explanation of the Voyager 1 early penetration into the LISM. We also show that there is a possibility that the spacecraft may enter the SW again before it finally leaves the heliosphere. We demonstrate a spontaneous transition to chaotic behavior in the heliosheath region covered by the heliospheric current sheet. Additionally, we analyze the behavior of the heliopause in the heliotail and show that it becomes violently unstable beyond 1000 AU, which results in the interpenetration of the solar and interstellar plasma.