The Link between Nonthermal Velocity and Free Magnetic Energy in Solar Flares
The cause of excess spectral line broadening (nonthermal velocity) is not definitively known, but given its rise before and during flaring, the causal processes hold clues to understanding the triggers for the onset of reconnection and the release of free magnetic energy from the coronal magnetic fi...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/ad1bee |
| _version_ | 1797349018134642688 |
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| author | James McKevitt Robert Jarolim Sarah Matthews Deborah Baker Manuela Temmer Astrid Veronig Hamish Reid Lucie Green |
| author_facet | James McKevitt Robert Jarolim Sarah Matthews Deborah Baker Manuela Temmer Astrid Veronig Hamish Reid Lucie Green |
| author_sort | James McKevitt |
| collection | DOAJ |
| description | The cause of excess spectral line broadening (nonthermal velocity) is not definitively known, but given its rise before and during flaring, the causal processes hold clues to understanding the triggers for the onset of reconnection and the release of free magnetic energy from the coronal magnetic field. A comparison of data during a 9 hr period from the extreme ultraviolet Imaging Spectrometer on the Hinode spacecraft—at a 3 minute cadence—and nonlinear force-free field extrapolations performed on Helioseismic and Magnetic Imager magnetograms—at a 12 minute cadence—shows an inverse relationship between nonthermal velocity and free magnetic energy on short timescales during two X-class solar flares on 2017 September 6. Analysis of these results supports suggestions that unresolved Doppler flows do not solely cause nonthermal broadening, and instead other mechanisms like Alfvén wave propagation and isotropic turbulence have a greater influence. |
| first_indexed | 2024-03-08T12:24:03Z |
| format | Article |
| id | doaj.art-3cdb509c8d764419936e628f8eb28ee4 |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-08T12:24:03Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-3cdb509c8d764419936e628f8eb28ee42024-01-22T12:50:51ZengIOP PublishingThe Astrophysical Journal Letters2041-82052024-01-019612L2910.3847/2041-8213/ad1beeThe Link between Nonthermal Velocity and Free Magnetic Energy in Solar FlaresJames McKevitt0https://orcid.org/0000-0002-4071-5727Robert Jarolim1https://orcid.org/0000-0002-9309-2981Sarah Matthews2https://orcid.org/0000-0001-9346-8179Deborah Baker3https://orcid.org/0000-0002-0665-2355Manuela Temmer4https://orcid.org/0000-0003-4867-7558Astrid Veronig5https://orcid.org/0000-0003-2073-002XHamish Reid6https://orcid.org/0000-0002-6287-3494Lucie Green7https://orcid.org/0000-0002-0053-4876University College London , Mullard Space Science Laboratory Holmbury St Mary, Dorking Surrey, RH5 6NT, UK ; james.mckevitt.21@ucl.ac.uk; University of Vienna , Institute of Astrophysics Türkenschanzstrasse 17 Vienna A-1180, AustriaUniversity of Graz , Institute of Physics Universitätsplatz 5 Graz A-8010, AustriaUniversity College London , Mullard Space Science Laboratory Holmbury St Mary, Dorking Surrey, RH5 6NT, UK ; james.mckevitt.21@ucl.ac.ukUniversity College London , Mullard Space Science Laboratory Holmbury St Mary, Dorking Surrey, RH5 6NT, UK ; james.mckevitt.21@ucl.ac.ukUniversity of Graz , Institute of Physics Universitätsplatz 5 Graz A-8010, AustriaUniversity of Graz , Institute of Physics Universitätsplatz 5 Graz A-8010, AustriaUniversity College London , Mullard Space Science Laboratory Holmbury St Mary, Dorking Surrey, RH5 6NT, UK ; james.mckevitt.21@ucl.ac.ukUniversity College London , Mullard Space Science Laboratory Holmbury St Mary, Dorking Surrey, RH5 6NT, UK ; james.mckevitt.21@ucl.ac.ukThe cause of excess spectral line broadening (nonthermal velocity) is not definitively known, but given its rise before and during flaring, the causal processes hold clues to understanding the triggers for the onset of reconnection and the release of free magnetic energy from the coronal magnetic field. A comparison of data during a 9 hr period from the extreme ultraviolet Imaging Spectrometer on the Hinode spacecraft—at a 3 minute cadence—and nonlinear force-free field extrapolations performed on Helioseismic and Magnetic Imager magnetograms—at a 12 minute cadence—shows an inverse relationship between nonthermal velocity and free magnetic energy on short timescales during two X-class solar flares on 2017 September 6. Analysis of these results supports suggestions that unresolved Doppler flows do not solely cause nonthermal broadening, and instead other mechanisms like Alfvén wave propagation and isotropic turbulence have a greater influence.https://doi.org/10.3847/2041-8213/ad1beeSolar extreme ultraviolet emissionSolar active region magnetic fields |
| spellingShingle | James McKevitt Robert Jarolim Sarah Matthews Deborah Baker Manuela Temmer Astrid Veronig Hamish Reid Lucie Green The Link between Nonthermal Velocity and Free Magnetic Energy in Solar Flares The Astrophysical Journal Letters Solar extreme ultraviolet emission Solar active region magnetic fields |
| title | The Link between Nonthermal Velocity and Free Magnetic Energy in Solar Flares |
| title_full | The Link between Nonthermal Velocity and Free Magnetic Energy in Solar Flares |
| title_fullStr | The Link between Nonthermal Velocity and Free Magnetic Energy in Solar Flares |
| title_full_unstemmed | The Link between Nonthermal Velocity and Free Magnetic Energy in Solar Flares |
| title_short | The Link between Nonthermal Velocity and Free Magnetic Energy in Solar Flares |
| title_sort | link between nonthermal velocity and free magnetic energy in solar flares |
| topic | Solar extreme ultraviolet emission Solar active region magnetic fields |
| url | https://doi.org/10.3847/2041-8213/ad1bee |
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