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Direct observation of turbulent magnetic reconnection in the solar wind

Abstract

Magnetic reconnection in a current sheet is commonly found in astrophysical plasma environments. If it is often bursty, releasing magnetic free energy explosively, in planetary magnetospheres, it instead displays a quasi-steady state in the solar wind, where the energy is dissipated via slow-mode shocks. The reason for this difference is elusive. Here we present a direct observation of bursty and turbulent magnetic reconnection in the solar wind, with its associated exhausts bounded by a pair of slow-mode shocks. We infer that the plasma is more efficiently heated in the magnetic reconnection diffusion region than across the shocks and that the flow enhancement is much higher in the exhausts than in the area around the diffusion region. We detected 75 other, similar diffusion-region events in solar wind data between October 2017 and May 2019, suggesting that bursty reconnection in the solar wind is more common than previously thought and actively contributes to solar wind acceleration and heating.

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Fig. 1: A schematic of the HCS and the reconnection paradigm within it.
Fig. 2: Overview of the reconnection event in the solar wind.
Fig. 3: Measurements of turbulent reconnection.
Fig. 4: Measurements in the reconnection diffusion region.
Fig. 5: Filamentary currents and magnetic flux ropes inside the electron diffusion region.
Fig. 6: Statistical analysis of the reconnection diffusion region in the solar wind.

Data availability

All MMS data are available at https://lasp.colorado.edu/mms/sdc/public/.

Code availability

All the figures were made with the SPEDAS software (Space Physics Environment Data Analysis Software), downloaded from http://spedas.org/blog/.

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Acknowledgements

This work is supported by the B-type Strategic Priority Program of the Chinese Academy of Sciences (XDB41000000; R.W.), the National Science Foundation of China (NSFC) (grants 41922030 and 42174187; R.W.), the key research programme of frontier sciences CAS (QYZDJ-SSW-DQC010; Q.L.), the Fundamental Research Funds for the Central Universities (R.W.) and the China-Brazil Joint Laboratory for Space Weather and the NSSC/CAS (W.G.). R.W. thanks O. Roberts and R. Nakamura of the Space Research Institute of the Austrian Academy of Sciences for fruitful discussion.

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R.W. carried out the spacecraft data analysis and interpretation and wrote the manuscript. S.W. and X.L. dealt with part of the spacecraft data and took part in the discussion. Q.L. supervised the work and provided the theoretical analysis. X.L and S.L took part in the discussion and gave valuable suggestions. W.G. gave valuable suggestions and comments. All the authors discussed the results and commented on the paper.

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Correspondence to Rongsheng Wang or Quanming Lu.

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Nature Astronomy thanks Lingling Zhao, Rungployphan Kieokaew and Zoltan Vörös for their contribution to the peer review of this work.

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Supplementary Figs. 1–5 and Tables 1–3.

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Wang, R., Wang, S., Lu, Q. et al. Direct observation of turbulent magnetic reconnection in the solar wind. Nat Astron 7, 18–28 (2023). https://doi.org/10.1038/s41550-022-01818-5

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