Continuum Enhancements, Line Profiles, and Magnetic Field Evolution during Consecutive Flares

Zuccarello, F.; Guglielmino, Salvo L.; Capparelli, V.; Mathioudakis, M.; Keys, Peter H.; Criscuoli, S.; Falco, M.; Murabito, M.

doi:10.3847/1538-4357/ab621f

Cited by 5 publications

(6 citation statements)

References 97 publications

(89 reference statements)

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“…IRIS observes substructures moving bi-directionally along the flare ribbons in a couple of events, indicating that reconnection in the quasi-separatrix layer between two flux systems has caused slip-running reconnection to occur (Li et al, 2018b(Li et al, , 2019b. A fan-spine topology was identified in another event using IRIS 2796 Å SJI observations, and because of this topology, slip-running reconnection is identified as a possible trigger mechanism (Zuccarello et al, 2020).…”

Section: Initiation Of Coronal Mass Ejections and Flaresmentioning

confidence: 93%

A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS)

et al. 2021

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The Interface Region Imaging Spectrograph (IRIS) has been obtaining near- and far-ultraviolet images and spectra of the solar atmosphere since July 2013. IRIS is the highest resolution observatory to provide seamless coverage of spectra and images from the photosphere into the low corona. The unique combination of near- and far-ultraviolet spectra and images at sub-arcsecond resolution and high cadence allows the tracing of mass and energy through the critical interface between the surface and the corona or solar wind. IRIS has enabled research into the fundamental physical processes thought to play a role in the low solar atmosphere such as ion–neutral interactions, magnetic reconnection, the generation, propagation, and dissipation of waves, the acceleration of non-thermal particles, and various small-scale instabilities. IRIS has provided insights into a wide range of phenomena including the discovery of non-thermal particles in coronal nano-flares, the formation and impact of spicules and other jets, resonant absorption and dissipation of Alfvénic waves, energy release and jet-like dynamics associated with braiding of magnetic-field lines, the role of turbulence and the tearing-mode instability in reconnection, the contribution of waves, turbulence, and non-thermal particles in the energy deposition during flares and smaller-scale events such as UV bursts, and the role of flux ropes and various other mechanisms in triggering and driving CMEs. IRIS observations have also been used to elucidate the physical mechanisms driving the solar irradiance that impacts Earth’s upper atmosphere, and the connections between solar and stellar physics. Advances in numerical modeling, inversion codes, and machine-learning techniques have played a key role. With the advent of exciting new instrumentation both on the ground, e.g. the Daniel K. Inouye Solar Telescope (DKIST) and the Atacama Large Millimeter/submillimeter Array (ALMA), and space-based, e.g. the Parker Solar Probe and the Solar Orbiter, we aim to review new insights based on IRIS observations or related modeling, and highlight some of the outstanding challenges.

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Section: Initiation Of Coronal Mass Ejections and Flaresmentioning

confidence: 93%

A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS)

et al. 2021

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“…The HMI continuum intensity measurements are well known to produce artifacts when fast phenomena occur, such as flares (e.g., Martínez Oliveros et al 2014). Different processes such as mass motions, gradients in temperature and the magnetic field and in some cases lines in emission might produce complex signatures in the spectral lines (e.g., Mauas 1990;Zuccarello et al 2020). For example, Švanda et al (2018) studied the intensity of the 6 HMI passbands and the derived continuum emission during a large flare and compared it to Hinode/SP spectra and simulated HMI spectra where the iron lines were in emission.…”

Section: Possible Sources Of Error and Reliability Of Hmi's Data Duri...mentioning

confidence: 99%

The Statistical Relationship between White-light Emission and Photospheric Magnetic Field Changes in Flares

Durán

Kleint

2020

ApJ

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Continuum emission, also called white-light emission (WLE), and permanent changes of the magnetic field (∆B LOS ) are often observed during solar flares. But their relation and their precise mechanisms are still unknown. We study statistically the relationship between ∆B LOS and WLE during 75 solar flares of different strengths and locations on the solar disk. We analyze SDO/HMI data and determine for each pixel in each flare if it exhibited WLE and/or ∆B LOS . We then investigate the occurrence, strength, and spatial size of the WLE, its dependence on flare energy, and its correlation to the occurrence of ∆B LOS . We detected WLE in 44/75 flares and ∆B LOS in 59/75 flares. We find that WLE and ∆B LOS are related, and their locations often overlap between 0-60%. Not all locations coincide, thus potentially indicating differences in their origin. We find that the WL area is related to the flare class by a power law and extend the findings of previous studies, that the WLE is related to the flare class by a power law, to also be valid for C-class flares. To compare unresolved (Sun-as-a-star) WL measurements to our data, we derive a method to calculate temperatures and areas of such data under the black-body assumption. The calculated unresolved WLE areas improve, but still differ to the resolved flaring area by about a factor of 5-10 (previously 10-20), which could be explained by various physical or instrumental causes. This method could also be applied to stellar flares to determine their temperatures and areas independently.

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“…Wang et al (1994) showed impulsive magnetic shear enhancements along the flaring neutral line during six X-class flares, and Wang et al (2012) observed the rapid enhancement of magnetic shear in the localized region of the PIL during an X2.2 flare that occurred in NOAA 11158. This is mostly caused by the changes in the photospheric magnetic fields, especially the enhancement of horizontal magnetic fields near the PIL region (Wang et al 2012;Zuccarello et al 2020;Vasantharaju et al 2022), as a consequence of coronal implosion during flares (Hudson et al 2008). However, the result could be different if the analysis is extended from localized regions of the PIL to the whole flaring area.…”

Section: Magnetic Nonpotentiality and Confinednessmentioning

confidence: 99%

Confinedness of an X3.1-class Solar Flare Occurred in NOAA 12192: Analysis from Multi-instrument Observations

Vasantharaju¹,

Zuccarello

Ferrente³

et al. 2023

ApJ

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The nonassociation of coronal mass ejections with high energetic flares is sparse. For this reason, the magnetic conditions required for the confinedness of major flares is a topic of active research. Using multi-instrument observations, we investigated the evolution and effects of confinedness in an X3.1 flare, which occurred in active region (AR) 12192. The decrease of net fluxes in the brightening regions near the footpoints of the multisigmoidal AR in the photosphere and chromosphere, indicative of flux cancellation favoring tether-cutting reconnection (TCR), is observed using the magnetic field observations of HMI/SDO and SOT/Hinode, respectively. The analysis of spectropolarimetric data obtained by the Interferometric Bidimensional Spectrometer over the brightening regions suggests untwisting of field lines, which further supports TCR. Filaments near the polarity inversion line region, resulting from TCR of low-lying sheared loops, undergo merging and form an elongated filament. The temperature and density differences between the footpoints of the merged filament, revealed by DEM analysis, cause streaming and counterstreaming of the plasma flow along the filament and unload at its footpoints with an average velocity of ≈40 km s−1. This results in a decrease of the mass of the filament (density decreased by >50%), leading to its rise and expansion outward. However, due to strong strapping flux, the filament separates itself instead of erupting. Further, the evolution of nonpotential parameters describes the characteristics of confinedness of the flare. Our study suggests that the sigmoid–filament system exhibits upward catastrophe due to mass unloading but gets suppressed by strong confinement of the external poloidal field.

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Continuum Enhancements, Line Profiles, and Magnetic Field Evolution during Consecutive Flares

Cited by 5 publications

References 97 publications

A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS)

A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS)

The Statistical Relationship between White-light Emission and Photospheric Magnetic Field Changes in Flares

Confinedness of an X3.1-class Solar Flare Occurred in NOAA 12192: Analysis from Multi-instrument Observations

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