Magnetohydrodynamic Turbulence Formation in Solar Flares: 3D Simulation and Synthetic Observations
Turbulent plasma motion is common in the universe and invoked in solar flares to drive effective acceleration leading to high-energy electrons. Unresolved mass motions are frequently detected in flares from extreme ultraviolet (EUV) observations, which are often regarded as turbulence. However, how...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ac9b4e |
| _version_ | 1827827961179406336 |
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| author | W. Ruan L. Yan R. Keppens |
| author_facet | W. Ruan L. Yan R. Keppens |
| author_sort | W. Ruan |
| collection | DOAJ |
| description | Turbulent plasma motion is common in the universe and invoked in solar flares to drive effective acceleration leading to high-energy electrons. Unresolved mass motions are frequently detected in flares from extreme ultraviolet (EUV) observations, which are often regarded as turbulence. However, how this plasma turbulence forms during the flare is still largely a mystery. Here we successfully reproduce observed turbulence in our 3D magnetohydrodynamic simulation where the magnetic reconnection process is included. The turbulence forms as a result of an intricate nonlinear interaction between the reconnection outflows and the magnetic arcades below the reconnection site, in which the shear-flow-driven Kelvin–Helmholtz instability (KHI) plays a key role in generating turbulent vortices. The turbulence is produced above high-density flare loops and then propagates to chromospheric footpoints along the magnetic field as Alfvénic perturbations. High turbulent velocities above 200 km s ^−1 can be found around the termination shock, while the low atmosphere reaches turbulent velocities of 10 km s ^−1 at a layer where the number density is about 10 ^11 cm ^−3 . The turbulent region with maximum nonthermal velocity coincides with the region where the observed high-energy electrons are concentrated, demonstrating the potential role of turbulence in acceleration. Synthetic views in EUV and fitted Hinode-EUV Imaging Spectrometer spectra show excellent agreement with observational results. An energy analysis demonstrates that more than 10% of the reconnection-downflow kinetic energy can be converted to turbulent energy via KHI. |
| first_indexed | 2024-03-12T03:38:33Z |
| format | Article |
| id | doaj.art-4224375dc24c4f22a5a4697902c6720f |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T03:38:33Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-4224375dc24c4f22a5a4697902c6720f2023-09-03T13:06:14ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0194726710.3847/1538-4357/ac9b4eMagnetohydrodynamic Turbulence Formation in Solar Flares: 3D Simulation and Synthetic ObservationsW. Ruan0https://orcid.org/0000-0001-5045-827XL. Yan1R. Keppens2https://orcid.org/0000-0003-3544-2733Centre for Mathematical Plasma Astrophysics , Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium wenzhi.ruan@kuleuven.beKey Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences , People's Republic of ChinaCentre for Mathematical Plasma Astrophysics , Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium wenzhi.ruan@kuleuven.beTurbulent plasma motion is common in the universe and invoked in solar flares to drive effective acceleration leading to high-energy electrons. Unresolved mass motions are frequently detected in flares from extreme ultraviolet (EUV) observations, which are often regarded as turbulence. However, how this plasma turbulence forms during the flare is still largely a mystery. Here we successfully reproduce observed turbulence in our 3D magnetohydrodynamic simulation where the magnetic reconnection process is included. The turbulence forms as a result of an intricate nonlinear interaction between the reconnection outflows and the magnetic arcades below the reconnection site, in which the shear-flow-driven Kelvin–Helmholtz instability (KHI) plays a key role in generating turbulent vortices. The turbulence is produced above high-density flare loops and then propagates to chromospheric footpoints along the magnetic field as Alfvénic perturbations. High turbulent velocities above 200 km s ^−1 can be found around the termination shock, while the low atmosphere reaches turbulent velocities of 10 km s ^−1 at a layer where the number density is about 10 ^11 cm ^−3 . The turbulent region with maximum nonthermal velocity coincides with the region where the observed high-energy electrons are concentrated, demonstrating the potential role of turbulence in acceleration. Synthetic views in EUV and fitted Hinode-EUV Imaging Spectrometer spectra show excellent agreement with observational results. An energy analysis demonstrates that more than 10% of the reconnection-downflow kinetic energy can be converted to turbulent energy via KHI.https://doi.org/10.3847/1538-4357/ac9b4eMagnetohydrodynamicsSolar flaresSolar physics |
| spellingShingle | W. Ruan L. Yan R. Keppens Magnetohydrodynamic Turbulence Formation in Solar Flares: 3D Simulation and Synthetic Observations The Astrophysical Journal Magnetohydrodynamics Solar flares Solar physics |
| title | Magnetohydrodynamic Turbulence Formation in Solar Flares: 3D Simulation and Synthetic Observations |
| title_full | Magnetohydrodynamic Turbulence Formation in Solar Flares: 3D Simulation and Synthetic Observations |
| title_fullStr | Magnetohydrodynamic Turbulence Formation in Solar Flares: 3D Simulation and Synthetic Observations |
| title_full_unstemmed | Magnetohydrodynamic Turbulence Formation in Solar Flares: 3D Simulation and Synthetic Observations |
| title_short | Magnetohydrodynamic Turbulence Formation in Solar Flares: 3D Simulation and Synthetic Observations |
| title_sort | magnetohydrodynamic turbulence formation in solar flares 3d simulation and synthetic observations |
| topic | Magnetohydrodynamics Solar flares Solar physics |
| url | https://doi.org/10.3847/1538-4357/ac9b4e |
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