Call and Response: A Time-resolved Study of Chromospheric Evaporation in a Large Solar Flare

G., Sellers, Sean; Milligan, Ryan O.; McAteer, R. T. James

doi:10.3847/1538-4357/ac87a9

Cited by 5 publications

(6 citation statements)

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“…This suggests a transition from explosive to gentle evaporation. The durations of the fast and gentle velocity phases are consistent with previous reports (Fletcher et al 2013;Sellers et al 2022). The decrease in the nonthermal velocity for CE2 occurs without a significant decrease in the Doppler velocity, which suggests the presence-and corresponding reductionof turbulence (Polito et al 2019).…”

Section: Iris Spectra Of the Chromospheric Evaporationsupporting

confidence: 90%

From Chromospheric Evaporation to Coronal Rain: An Investigation of the Mass and Energy Cycle of a Flare

Şahin,

Antolin

2024

ApJ

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Chromospheric evaporation (CE) and coronal rain (CR) represent two crucial phenomena encompassing the circulation of mass and energy during solar flares. While CE marks the start of the hot inflow into the flaring loop, CR marks the end, indicating the outflow in the form of cool and dense condensations. With the Interface Region Imaging Spectrograph (IRIS) and the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory, we examine and compare the evolution, dynamics, morphology, and energetics of the CR and CE during a C2.1 flare. The CE is directly observed in imaging and spectra in the Fe xxi line with IRIS and in the Fe xviii line of AIA, with upward average total speeds of 138 ± 35 km s−1 and a temperature of 9.03 ± 3.28 × 106 K. An explosive-to-gentle CE transition is observed, with an apparent reduction in turbulence. From quiescent to gradual flare phase, the amount and density of CR increase by a factor of ≈4.4 and 6, respectively. The rain’s velocity increases by a factor of 1.4, in agreement with gas pressure drag. In contrast, the clump width variation is negligible. The location and morphology of CE match closely those of the rain showers, with similar CE substructure to the rain strands, reflecting fundamental scales of mass and energy transport. We obtain a CR outflow mass three times larger than the CE inflow mass, suggesting the presence of unresolved CE, perhaps at higher temperatures. The CR energy corresponds to half that of the CE. These results suggest an essential role of CR in the mass−energy cycle of a flare.

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Section: Iris Spectra Of the Chromospheric Evaporationsupporting

confidence: 90%

From Chromospheric Evaporation to Coronal Rain: An Investigation of the Mass and Energy Cycle of a Flare

Şahin,

Antolin

2024

ApJ

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“…In the footpoint of a C class flare, ions forming T > ∼1.5 MK exhibited large blueshifts whereas T < ∼1.5 MK exhibited redshifts (assuming ionisation equilibrium for their formation temperatures). Studying an Xclass flare in which EIS observed several footpoint sources (Sellers et al, 2022) found similar results but with a range of flow reversal temperatures T FR ∼[1. 35-1.82] MK.…”

Section: "Electron Beam" Driven Mass Flowsmentioning

confidence: 66%

“…As such, EUVST is very well placed to perform detailed studies of mass flows during flares that encompass simultaneously the chromosphere, transition region, and corona (with each layer sampled by many lines). Comprehensive analyses such as those performed by Milligan and Dennis (2009) and Sellers et al (2022) over this wide temperature range, and with higher spatiotemporal resolution, should be a priority to better understand the evolution of mass flows in flares. EUVST will be complemented by observations from the Multi-slit Solar Explorer (MUSE;De Pontieu et al, 2020;Cheung et al, 2022) which has a more limited temperature coverage, focussing on the corona and flare plasma, with one line sampling the transition region, but which has 37 slits, allowing imaging spectroscopy of an entire active region sized field of view to be performed in <12 s. MUSE observations of the flaring corona, covering the full flaring structure, will hopefully shed light on continued energy release in the post-impulsive phase.…”

Section: Discussionmentioning

confidence: 99%

“…In their study Allred et al (2022) included the turbulent mean free path in the line synthesis, acting as a source of nonthermal broadening. Sellers et al (2022) performed a very detailed observational study of the flows from many lines as observed by EIS and IRIS, as well as analysing the hard Xray observations from RHESSI. Modelling those various flare footpoints, driven by non-thermal electron distributions inferred from the RHESSI observations as a function of time [for example using the RADYN_Arcade framework of Kerr et al (2020), see below] would be a worthwhile endeavour to explore the pattern of upflows versus downflows.…”

Section: "Electron Beam" Driven Mass Flowsmentioning

confidence: 99%

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Interrogating solar flare loop models with IRIS observations 1: Overview of the models, and mass flows

Kerr

2022

Front. Astron. Space Sci.

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Solar flares are transient yet dramatic events in the atmosphere of the Sun, during which a vast amount of magnetic energy is liberated. This energy is subsequently transported through the solar atmosphere or into the heliosphere, and together with coronal mass ejections flares comprise a fundamental component of space weather. Thus, understanding the physical processes at play in flares is vital. That understanding often requires the use of forward modelling in order to predict the hydrodynamic and radiative response of the solar atmosphere. Those predictions must then be critiqued by observations to show us where our models are missing ingredients. While flares are of course 3D phenomenon, simulating the flaring atmosphere including an accurate chromosphere with the required spatial scales in 3D is largely beyond current computational capabilities, and certainly performing parameter studies of energy transport mechanisms is not yet tractable in 3D. Therefore, field-aligned 1D loop models that can resolve the relevant scales have a crucial role to play in advancing our knowledge of flares. In recent years, driven in part by the spectacular observations from the Interface Region Imaging Spectrograph (IRIS), flare loop models have revealed many interesting features of flares. For this review I highlight some important results that illustrate the utility of attacking the problem of solar flares with a combination of high quality observations, and state-of-the-art flare loop models, demonstrating: 1) how models help to interpret flare observations from IRIS, 2) how those observations show us where we are missing physics from our models, and 3) how the ever increasing quality of solar observations drives model improvements. Here in Paper one of this two part review I provide an overview of modern flare loop models, and of electron-beam driven mass flows during solar flares.

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“…In the case of explosive chromospheric evaporation, chromospheric plasmas are rapidly heated, resulting in a much higher pressure in the chromosphere. Then, some plasmas expand upward into the low-density corona at fast velocities of several hundred km s −1 , while some other plasmas precipitate downward with a slow velocity of a few tens km s −1 into the high-density chromosphere due to momentum conservation (e.g., Veronig et al 2010;Brosius & Inglis 2017;Tian & Chen 2018;Sellers et al 2022). That is, the upflows driven by chromospheric evaporation and the downflows caused by chromospheric condensation can be simultaneously observed in an explosive evaporation event.…”

Section: Introductionmentioning

confidence: 99%

Observational Signatures of Electron-driven Chromospheric Evaporation in a White-light Flare

Li,

Qiu

et al. 2023

ApJ

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We investigate observational signatures of explosive chromospheric evaporation during a white-light flare (WLF) that occurred on 2022 August 27. Using the moment analysis, bisector techniques, and the Gaussian fitting method, redshifted velocities of less than 20 km s−1 are detected in low-temperature spectral lines of Hα, C i, and Si iv at the conjugated flare kernels, which could be regarded as downflows caused by chromospheric condensation. Blueshifted velocities of ∼30−40 km s−1 are found in the high-temperature line of Fe xxi, which can be interpreted as upflows driven by chromospheric evaporation. A nonthermal hard X-ray (HXR) source is cospatial with one of the flare kernels, and the Doppler velocities are temporally correlated with the HXR fluxes. The nonthermal energy flux is estimated to be at least (1.3 ± 0.2) × 1010 erg s−1 cm−2. The radiation enhancement at Fe i 6569.2 Å and 6173 Å suggests that the flare is a WLF. Moreover, the while-light emission at Fe i 6569.2 Å is temporally and spatially correlated with the blueshift of the Fe xxi line, suggesting that both the white-light enhancement and the chromospheric evaporation are triggered and driven by nonthermal electrons. All of our observations support the scenario of an electron-driven explosive chromospheric evaporation in the WLF.

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Call and Response: A Time-resolved Study of Chromospheric Evaporation in a Large Solar Flare

Cited by 5 publications

References 92 publications

From Chromospheric Evaporation to Coronal Rain: An Investigation of the Mass and Energy Cycle of a Flare

From Chromospheric Evaporation to Coronal Rain: An Investigation of the Mass and Energy Cycle of a Flare

Interrogating solar flare loop models with IRIS observations 1: Overview of the models, and mass flows

Observational Signatures of Electron-driven Chromospheric Evaporation in a White-light Flare

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