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Peer-reviewedCC BY 4.0The Astrophysical Journal Letters

Nonlocal Evolution of Magnetic Helicity across the Magnetohydrodynamic–Kinetic Interface

  • Masatomi Iizawa1
  • Yasuhito Narita1,2
  • Tommaso Alberti3
  • Stuart D. Bale4
  • Axel Brandenburg5,6,7,8
  • Abraham C.-L. Chian9,10
  • Horia Comişel11
  • Shuichi Matsukiyo12,13
  • Nobumitsu Yokoi5,14,15,16
16 affiliations
  1. 1Technische Universität Braunschweig
  2. 2Max Planck Institute for Solar System Research
  3. 3Istituto Nazionale di Geofisica e Vulcanologia
  4. 4University of California
  5. 5KTH Royal Institute of Technology and Stockholm University
  6. 6Stockholm University
  7. 7Ilia State University
  8. 8Carnegie Mellon University
  9. 9Adelaide University
  10. 10National Institute for Space Research (INPE)
  11. 11Institute for Space Sciences
  12. 12Kyushu University
  13. 13Osaka University
  14. 14University of Tokyo
  15. 15Tohoku University
  16. 16Université de Lyon
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Abstract

Magnetic helicity is typically indistinguishable from noise in the solar wind inertial range. Using Parker Solar Probe measurements (0.1–0.8 au), we report a robust bihelical structure emerging at the magnetohydrodynamic (MHD)–kinetic interface. This structure, formed by a striking pair of positive and negative peaks, exhibits a systematic spectral migration toward lower frequencies with increasing heliocentric distance. Crucially, this evolution deviates from local kinetic scaling laws, such as the radial decline of the ion cyclotron frequency, reflecting a nonlocal evolution of magnetic topology. Our findings provide a new observational constraint on both nonlocal MHD transport processes and the nature of the helicity barrier in the kinetic regime.

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Cite

BibTeXRIS
BibTeX
@article{iizawa2026nonlocal,
  title = {{Nonlocal Evolution of Magnetic Helicity across the Magnetohydrodynamic–Kinetic Interface}},
  author = {Masatomi Iizawa and Yasuhito Narita and Tommaso Alberti and Stuart D. Bale and Axel Brandenburg and Abraham C.-L. Chian and Horia Comişel and Shuichi Matsukiyo and Nobumitsu Yokoi},
  journal = {The Astrophysical Journal Letters},
  year = {2026},
  month = oct,
  doi = {10.3847/2041-8213/aea84b},
  url = {https://iopscience.iop.org/article/10.3847/2041-8213/aea84b},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Nonlocal Evolution of Magnetic Helicity across the Magnetohydrodynamic–Kinetic Interface
AU  - Masatomi Iizawa
AU  - Yasuhito Narita
AU  - Tommaso Alberti
AU  - Stuart D. Bale
AU  - Axel Brandenburg
AU  - Abraham C.-L. Chian
AU  - Horia Comişel
AU  - Shuichi Matsukiyo
AU  - Nobumitsu Yokoi
PY  - 2026
DA  - 2026/10/13
JO  - The Astrophysical Journal Letters
DO  - 10.3847/2041-8213/aea84b
UR  - https://iopscience.iop.org/article/10.3847/2041-8213/aea84b
AB  - Magnetic helicity is typically indistinguishable from noise in the solar wind inertial range. Using Parker Solar Probe measurements (0.1–0.8 au), we report a robust bihelical structure emerging at the magnetohydrodynamic (MHD)–kinetic interface. This structure, formed by a striking pair of positive and negative peaks, exhibits a systematic spectral migration toward lower frequencies with increasing heliocentric distance. Crucially, this evolution deviates from local kinetic scaling laws, such as the radial decline of the ion cyclotron frequency, reflecting a nonlocal evolution of magnetic topology. Our findings provide a new observational constraint on both nonlocal MHD transport processes and the nature of the helicity barrier in the kinetic regime.
SN  - 2041-8205
SN  - 2041-8213
ER  -