Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadence
We report on observations of highly-varying Si IV 1402.77 Å line profiles observed with the Interface Region Imaging Spectrograph (IRIS) during the M-class flare from 18 January 2022 at an unprecedented 0.8 s cadence. Moment analysis of this line observed in flare ribbon kernels showed that the inte...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2022-11-01
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| Series: | Frontiers in Astronomy and Space Sciences |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fspas.2022.1040945/full |
| _version_ | 1811313868483330048 |
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| author | Juraj Lörinčík Juraj Lörinčík Vanessa Polito Vanessa Polito Vanessa Polito Bart De Pontieu Bart De Pontieu Bart De Pontieu Sijie Yu Nabil Freij Nabil Freij |
| author_facet | Juraj Lörinčík Juraj Lörinčík Vanessa Polito Vanessa Polito Vanessa Polito Bart De Pontieu Bart De Pontieu Bart De Pontieu Sijie Yu Nabil Freij Nabil Freij |
| author_sort | Juraj Lörinčík |
| collection | DOAJ |
| description | We report on observations of highly-varying Si IV 1402.77 Å line profiles observed with the Interface Region Imaging Spectrograph (IRIS) during the M-class flare from 18 January 2022 at an unprecedented 0.8 s cadence. Moment analysis of this line observed in flare ribbon kernels showed that the intensity, Doppler velocity, and non-thermal broadening exhibited variations with periods below 10 s. These variations were found to be correlated with properties of the Gaussian fit to a well-resolved secondary component of the line redshifted by up to 70 km s−1, while the primary component was consistently observed near the rest wavelength of the line. A particularly high correlation was found between the non-thermal broadening of the line resulting from the moment analysis and the redshift of the secondary component. This means that the oscillatory enhancements in the line broadening were due to plasma flows (away from the observer) with varying properties. A simple de-projection of the Doppler velocities of the secondary component based on a three-dimensional reconstruction of flare loops rooted in the kernel suggests that the observed flows were caused by downflows and compatible with strong condensation flows recently predicted by numerical simulations. Furthermore, peaks of the intensity and the trends of Doppler velocity of the Gaussian fit to the secondary component (averaged in the ribbon) were found to correspond to one of the quasi-periodic pulsations (QPPs) detected during the event in the soft X-ray flux (as measured by the Geostationary Operational Environmental Satellite, GOES) and the microwave radio flux (as measured by the Expanded Owens Valley Solar Array, EOVSA). This result supports a scenario in which the QPPs were driven by repeated magnetic reconnection. |
| first_indexed | 2024-04-13T11:02:10Z |
| format | Article |
| id | doaj.art-90f262f5eca84120b49c614c3605e9e1 |
| institution | Directory Open Access Journal |
| issn | 2296-987X |
| language | English |
| last_indexed | 2024-04-13T11:02:10Z |
| publishDate | 2022-11-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Astronomy and Space Sciences |
| spelling | doaj.art-90f262f5eca84120b49c614c3605e9e12022-12-22T02:49:22ZengFrontiers Media S.A.Frontiers in Astronomy and Space Sciences2296-987X2022-11-01910.3389/fspas.2022.10409451040945Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadenceJuraj Lörinčík0Juraj Lörinčík1Vanessa Polito2Vanessa Polito3Vanessa Polito4Bart De Pontieu5Bart De Pontieu6Bart De Pontieu7Sijie Yu8Nabil Freij9Nabil Freij10Bay Area Environmental Research Institute, NASA Research Park, Moffett Field, CA, United StatesLockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA, United StatesBay Area Environmental Research Institute, NASA Research Park, Moffett Field, CA, United StatesLockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA, United StatesDepartment of Physics, Oregon State University, Corvallis, OR, United StatesLockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA, United StatesInstitute of Theoretical Astrophysics, University of Oslo, Oslo, NorwayRosseland Centre for Solar Physics, University of Oslo, Oslo, NorwayCenter for Solar-Terrestrial Research, New Jersey Institute of Technology, Newark, NJ, United StatesBay Area Environmental Research Institute, NASA Research Park, Moffett Field, CA, United StatesLockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA, United StatesWe report on observations of highly-varying Si IV 1402.77 Å line profiles observed with the Interface Region Imaging Spectrograph (IRIS) during the M-class flare from 18 January 2022 at an unprecedented 0.8 s cadence. Moment analysis of this line observed in flare ribbon kernels showed that the intensity, Doppler velocity, and non-thermal broadening exhibited variations with periods below 10 s. These variations were found to be correlated with properties of the Gaussian fit to a well-resolved secondary component of the line redshifted by up to 70 km s−1, while the primary component was consistently observed near the rest wavelength of the line. A particularly high correlation was found between the non-thermal broadening of the line resulting from the moment analysis and the redshift of the secondary component. This means that the oscillatory enhancements in the line broadening were due to plasma flows (away from the observer) with varying properties. A simple de-projection of the Doppler velocities of the secondary component based on a three-dimensional reconstruction of flare loops rooted in the kernel suggests that the observed flows were caused by downflows and compatible with strong condensation flows recently predicted by numerical simulations. Furthermore, peaks of the intensity and the trends of Doppler velocity of the Gaussian fit to the secondary component (averaged in the ribbon) were found to correspond to one of the quasi-periodic pulsations (QPPs) detected during the event in the soft X-ray flux (as measured by the Geostationary Operational Environmental Satellite, GOES) and the microwave radio flux (as measured by the Expanded Owens Valley Solar Array, EOVSA). This result supports a scenario in which the QPPs were driven by repeated magnetic reconnection.https://www.frontiersin.org/articles/10.3389/fspas.2022.1040945/fullsolar flaressolar atmospheresolar ultraviolet emissionsolar transition regionsolar magnetic reconnection |
| spellingShingle | Juraj Lörinčík Juraj Lörinčík Vanessa Polito Vanessa Polito Vanessa Polito Bart De Pontieu Bart De Pontieu Bart De Pontieu Sijie Yu Nabil Freij Nabil Freij Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadence Frontiers in Astronomy and Space Sciences solar flares solar atmosphere solar ultraviolet emission solar transition region solar magnetic reconnection |
| title | Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadence |
| title_full | Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadence |
| title_fullStr | Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadence |
| title_full_unstemmed | Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadence |
| title_short | Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadence |
| title_sort | rapid variations of si iv spectra in a flare observed by interface region imaging spectrograph at a sub second cadence |
| topic | solar flares solar atmosphere solar ultraviolet emission solar transition region solar magnetic reconnection |
| url | https://www.frontiersin.org/articles/10.3389/fspas.2022.1040945/full |
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