A Model for Gradual-phase Heating Driven by MHD Turbulence in Solar Flares
Coronal flare emission is commonly observed to decay on timescales longer than those predicted by impulsively driven, one-dimensional flare loop models. This discrepancy is most apparent during the gradual phase, where emission from these models decays over minutes, in contrast to the hour or more o...
| 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/acb1b2 |
| _version_ | 1797697212538421248 |
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| author | William Ashfield IV Dana Longcope |
| author_facet | William Ashfield IV Dana Longcope |
| author_sort | William Ashfield IV |
| collection | DOAJ |
| description | Coronal flare emission is commonly observed to decay on timescales longer than those predicted by impulsively driven, one-dimensional flare loop models. This discrepancy is most apparent during the gradual phase, where emission from these models decays over minutes, in contrast to the hour or more often observed. Magnetic reconnection is invoked as the energy source of a flare, but should deposit energy into a given loop within a matter of seconds. Models which supplement this impulsive energization with a long, persistent ad hoc heating have successfully reproduced long-duration emission, but without providing a clear physical justification. Here we propose a model for extended flare heating by the slow dissipation of turbulent Alfvén waves initiated during the retraction of newly reconnected flux tubes through a current sheet. Using one-dimensional simulations, we track the production and evolution of MHD wave turbulence trapped by reflection from high-density gradients in the transition region. Turbulent energy dissipates through nonlinear interaction between counter-propagating waves, modeled here using a phenomenological one-point closure model. Atmospheric Imaging Assembly EUV light curves synthesized from the simulation were able to reproduce emission decay on the order of tens of minutes. We find this simple model offers a possible mechanism for generating the extended heating demanded by observed coronal flare emissions self-consistently from reconnection-powered flare energy release. |
| first_indexed | 2024-03-12T03:37:03Z |
| format | Article |
| id | doaj.art-c4223a0b5e9448e38bd63da28805e491 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T03:37:03Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-c4223a0b5e9448e38bd63da28805e4912023-09-03T13:08:38ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01944214710.3847/1538-4357/acb1b2A Model for Gradual-phase Heating Driven by MHD Turbulence in Solar FlaresWilliam Ashfield IV0https://orcid.org/0000-0002-6368-939XDana Longcope1Bay Area Environmental Research Institute , NASA Research Park, Moffett Field, CA 94035, USA; Lockheed Martin Solar & Astrophysics Laboratory , Organization A021S, Building 252, 3251 Hanover Street, Palo Alto, CA 94304, USADepartment of Physics, Montana State University , Bozeman, MT 59717, USACoronal flare emission is commonly observed to decay on timescales longer than those predicted by impulsively driven, one-dimensional flare loop models. This discrepancy is most apparent during the gradual phase, where emission from these models decays over minutes, in contrast to the hour or more often observed. Magnetic reconnection is invoked as the energy source of a flare, but should deposit energy into a given loop within a matter of seconds. Models which supplement this impulsive energization with a long, persistent ad hoc heating have successfully reproduced long-duration emission, but without providing a clear physical justification. Here we propose a model for extended flare heating by the slow dissipation of turbulent Alfvén waves initiated during the retraction of newly reconnected flux tubes through a current sheet. Using one-dimensional simulations, we track the production and evolution of MHD wave turbulence trapped by reflection from high-density gradients in the transition region. Turbulent energy dissipates through nonlinear interaction between counter-propagating waves, modeled here using a phenomenological one-point closure model. Atmospheric Imaging Assembly EUV light curves synthesized from the simulation were able to reproduce emission decay on the order of tens of minutes. We find this simple model offers a possible mechanism for generating the extended heating demanded by observed coronal flare emissions self-consistently from reconnection-powered flare energy release.https://doi.org/10.3847/1538-4357/acb1b2Solar flaresMagnetohydrodynamical simulationsSolar extreme ultraviolet emission |
| spellingShingle | William Ashfield IV Dana Longcope A Model for Gradual-phase Heating Driven by MHD Turbulence in Solar Flares The Astrophysical Journal Solar flares Magnetohydrodynamical simulations Solar extreme ultraviolet emission |
| title | A Model for Gradual-phase Heating Driven by MHD Turbulence in Solar Flares |
| title_full | A Model for Gradual-phase Heating Driven by MHD Turbulence in Solar Flares |
| title_fullStr | A Model for Gradual-phase Heating Driven by MHD Turbulence in Solar Flares |
| title_full_unstemmed | A Model for Gradual-phase Heating Driven by MHD Turbulence in Solar Flares |
| title_short | A Model for Gradual-phase Heating Driven by MHD Turbulence in Solar Flares |
| title_sort | model for gradual phase heating driven by mhd turbulence in solar flares |
| topic | Solar flares Magnetohydrodynamical simulations Solar extreme ultraviolet emission |
| url | https://doi.org/10.3847/1538-4357/acb1b2 |
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