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Peer-reviewedCC BY 4.0The Astrophysical Journal

Turbulence and Intermittency Driven By Instabilities of the Heliospheric Jets

  • Xiaohan Ma1
  • Lingling Zhao2
  • Merav Opher1
  1. 1Boston University
  2. 2The University of Alabama in Huntsville
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Abstract

The shape and structure of the heliosphere remain under debate, particularly regarding the formation of heliospheric jets and the existence of an open heliotail. Plasma instabilities and turbulent-like dynamics may provide key insights into these unresolved questions. In this work, we use long-term magnetohydrodynamic (MHD) simulations to further investigate the coupled evolution of Rayleigh–Taylor (RT) and Kelvin–Helmholtz (KH) instabilities in the heliosphere and explore their roles in generating and shaping turbulent-like fluctuations in the heliosheath (HS). The results reveal distinct scale-dependent regimes that evolve with the instabilities. The power spectral density (PSD) of magnetic field fluctuation exhibits an approximately k ⁻¹ scaling at scales ≳40 au, a steeper scaling close to k −8/3 at intermediate scales of 15–40 au, and a gradual transition toward a Kolmogorov-like k −5/3 scaling at smaller scales of 6–15 au. The intermediate-scale fluctuations remain influenced by instability-driven coherent structures, whereas increasingly turbulent-like characteristics emerge toward smaller scales. The flatness remains near the Gaussian baseline ( F = 3) at large scales but increases above 3 at smaller scales, indicating the emergence of intermittency. The long-term evolution further shows that enhanced flatness and spectral steepening are correlated with recurrent HS instability cycles. These results suggest that the HS exhibits instability-modulated, turbulent-like dynamics, in which large-scale RT/KH-driven coherent structures recurrently evolve and fragment into increasingly complex fluctuations at smaller scales, providing a possible pathway for energy redistribution across spatial scales.

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Cite

BibTeXRIS
BibTeX
@article{ma2026turbulence,
  title = {{Turbulence and Intermittency Driven By Instabilities of the Heliospheric Jets}},
  author = {Xiaohan Ma and Lingling Zhao and Merav Opher},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/aeac57},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeac57},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Turbulence and Intermittency Driven By Instabilities of the Heliospheric Jets
AU  - Xiaohan Ma
AU  - Lingling Zhao
AU  - Merav Opher
PY  - 2026
DA  - 2026/10/27
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/aeac57
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/aeac57
AB  - The shape and structure of the heliosphere remain under debate, particularly regarding the formation of heliospheric jets and the existence of an open heliotail. Plasma instabilities and turbulent-like dynamics may provide key insights into these unresolved questions. In this work, we use long-term magnetohydrodynamic (MHD) simulations to further investigate the coupled evolution of Rayleigh–Taylor (RT) and Kelvin–Helmholtz (KH) instabilities in the heliosphere and explore their roles in generating and shaping turbulent-like fluctuations in the heliosheath (HS). The results reveal distinct scale-dependent regimes that evolve with the instabilities. The power spectral density (PSD) of magnetic field fluctuation exhibits an approximately k ⁻¹ scaling at scales ≳40 au, a steeper scaling close to k −8/3 at intermediate scales of 15–40 au, and a gradual transition toward a Kolmogorov-like k −5/3 scaling at smaller scales of 6–15 au. The intermediate-scale fluctuations remain influenced by instability-driven coherent structures, whereas increasingly turbulent-like characteristics emerge toward smaller scales. The flatness remains near the Gaussian baseline ( F = 3) at large scales but increases above 3 at smaller scales, indicating the emergence of intermittency. The long-term evolution further shows that enhanced flatness and spectral steepening are correlated with recurrent HS instability cycles. These results suggest that the HS exhibits instability-modulated, turbulent-like dynamics, in which large-scale RT/KH-driven coherent structures recurrently evolve and fragment into increasingly complex fluctuations at smaller scales, providing a possible pathway for energy redistribution across spatial scales.
SN  - 1538-4357
SN  - 0004-637X
ER  -