The Coupling and Evolution of Kelvin–Helmholtz and Rayleigh–Taylor Instabilities in the Heliosheath
The shape and structure of the heliosphere remain subjects of ongoing debate, with current models differing on how far the heliospheric jets that form the two-lobe structure extend down the heliotail and whether the surrounding interstellar medium can penetrate the region between the lobes. Rayleigh...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ade881 |
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| Summary: | The shape and structure of the heliosphere remain subjects of ongoing debate, with current models differing on how far the heliospheric jets that form the two-lobe structure extend down the heliotail and whether the surrounding interstellar medium can penetrate the region between the lobes. Rayleigh–Taylor (RT) and Kelvin–Helmholtz (KH) instabilities along the axis of the heliospheric jets have been proposed as key drivers of turbulence in the heliosheath (HS). In this work, we present results from 225 yr MHD simulations that reveal periodic variations in solar wind speed and magnetic field within the HS, coinciding with the cyclic growth of RT and KH instabilities. At the onset of each cycle, the instabilities initially develop simultaneously in the direction normal to the plane of the heliospheric jet, with an average timescale of ∼4.2 yr. As the system evolves over ∼11.1 yr, RT and KH modes decouple, with KH modes subsequently dominating beyond the high-density region and leading to a reduced growth rate, corresponding to a timescale of ∼12.9 yr. These findings suggest that RT and KH instabilities can coevolve and reoccur periodically, contributing to turbulence generation in the HS. Their nonlinear development may play a fundamental role in shaping the large-scale structure of the heliosphere, particularly in the formation and evolution of the open heliospheric tail. |
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| ISSN: | 1538-4357 |