Interchange reconnection as the source of the fast solar wind within coronal holes
Abstract
The fast solar wind that fills the heliosphere originates from deep within regions of open magnetic field on the Sun called 'coronal holes'. The energy source responsible for accelerating the plasma is widely debated; however, there is evidence that it is ultimately magnetic in nature, with candidate mechanisms including wave heating and interchange reconnection. The coronal magnetic field near the solar surface is structured on scales associated with 'supergranulation' convection cells, whereby descending flows create intense fields. The energy density in these 'network' magnetic field bundles is a candidate energy source for the wind. Here we report measurements of fast solar wind streams from the Parker Solar Probe (PSP) spacecraft6 that provide strong evidence for the interchange reconnection mechanism. We show that the supergranulation structure at the coronal base remains imprinted in the near-Sun solar wind, resulting in asymmetric patches of magnetic 'switchbacks'7,8 and bursty wind streams with power-law-like energetic ion spectra to beyond 100 keV. Computer simulations of interchange reconnection support key features of the observations, including the ion spectra. Important characteristics of interchange reconnection in the low corona are inferred from the data, including that the reconnection is collisionless and that the energy release rate is sufficient to power the fast wind. In this scenario, magnetic reconnection is continuous and the wind is driven by both the resulting plasma pressure and the radial Alfvénic flow bursts.
Additional Information
© The Author(s) 2023. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The FIELDS, SWEAP and ISOIS suites were designed, developed and are operated under NASA contract NNN06AA01C. We acknowledge the extraordinary contributions of the PSP mission operations and spacecraft engineering team at the Johns Hopkins University Applied Physics Laboratory. M.V. was supported in part by the International Space Science Institute, Bern, through the J. Geiss fellowship. J.F.D. and M.S. were supported by the NASA Drive Science Center on Solar Flare Energy Release (SolFER) under Grant 80NSSC20K0627, NASA Grant 80NSSC22K0433 and NSF Grant PHY2109083. T.S.H. is supported by STFC grant ST/W001071/1. O.P. was supported by the NASA Grant 80NSSC20K1829. Elements of this work benefited from discussions at the meeting of Team 463 at the International Space Science Institute (ISSI). Contributions. S.D.B. and J.F.D. wrote the manuscript with major contributions from S.T.B. S.D.B. analysed the PSP measurements, with contributions from M.D.M., M.I.D., T.S.H. and D.E.L. S.T.B. performed the PFSS analysis. J.F.D. and M.S. performed the computer simulations. S.D.B., J.C.K. and D.J.M. lead the PSP/FIELDS, SWEAP and ISOIS teams, respectively. All authors participated in the data interpretation and read and commented on the manuscript. Data availability. The PSP mission data used in this study are openly available at the NASA Space Physics Data Facility (https://nssdc.gsfc.nasa.gov) and were analysed using the IDL/SPEDAS software package (https://spedas.org/blog/). The computer simulations used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US Department of Energy under contract no. DE-AC02- 05CH11231. Simulation data is available at https://doi.org/10.5281/zenodo.7562035. The authors declare no competing interests.Attached Files
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Additional details
- PMCID
- PMC10247371
- Eprint ID
- 122070
- Resolver ID
- CaltechAUTHORS:20230630-524899000.3
- NNN06AA01C
- NASA
- International Space Science Institute (ISSI)
- 80NSSC20K0627
- NASA
- 80NSSC22K0433
- NASA
- PHY-2109083
- NSF
- ST/W001071/1
- Science and Technology Facilities Council (STFC)
- 80NSSC20K1829
- NASA
- DE-AC02-05CH11231
- Department of Energy (DOE)
- Created
-
2023-07-01Created from EPrint's datestamp field
- Updated
-
2023-07-01Created from EPrint's last_modified field
- Caltech groups
- Space Radiation Laboratory