A comprehensive three-dimensional radiative magnetohydrodynamic simulation of a solar flare

Cheung, Mark C. M.; Rempel, Matthias; Chintzoglou, Georgios; Chen, F.; Testa, Paola; Martínez-Sykora, Juan; Dalda, A. Sainz; DeRosa, Marc L.; Malanushenko, Anna; Hansteen, V. H.; Pontieu, Bart De; Carlsson, Mats; Gudiksen, B. V.; McIntosh, Scott W.

doi:10.1038/s41550-018-0629-3

Cited by 155 publications

(132 citation statements)

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“…Further, one might ask whether our results might be affected by the limitation of 1D codes to capture 3D structures and geometries of the lower atmospheric regions. A preliminary analysis based on IRIS Fe XXI1354.1 Å synthetic spectra from a 3D MHD simulation by Cheung et al (2019) of a flare heated by thermal conduction shows similar results to those obtained in this work, namely that the blueshifted and broad Fe XXIprofiles at the flare ribbons are also mostly asymmetric. Even though these are preliminary results and will be expanded in a follow-up work, they support our results and suggest that the asymmetry of the lines does not seem to significantly depend on the exact details of the heating model or the choice of tilt angles.…”

Section: Discussion and Summarysupporting

confidence: 82%

Can the Superposition of Evaporative Flows Explain Broad Fe xxi Profiles during Solar Flares?

Polito

Testa

Pontieu

2019

ApJL

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The observation of the high-temperature (10 MK) Fe XXI1354.1 Å line with the Interface Region Imaging Spectrograph has provided significant insights into the chromospheric evaporation process in flares. In particular, the line is often observed to be completely blueshifted, in contrast to previous observations at lower spatial and spectral resolution, and in agreement with predictions from theoretical models. Interestingly, the line is also observed to be mostly symmetric and significantly broader than expected from thermal motions (assuming the peak formation temperature of the ion is in equilibrium). One popular interpretation for the nonthermal broadening is the superposition of flows from different loop strands.In this work, we test this scenario by forward-modeling the Fe XXIline profile assuming different possible observational scenarios using hydrodynamic simulations of multithread flare loops with the 1D RADYN code. Our results indicate that the superposition of flows alone cannot easily reproduce both the symmetry and the significant broadening of the line and that some other physical process, such as turbulence, or a much larger ion temperature than previously expected, likely needs to be invoked in order to explain the observed profiles.

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Section: Discussion and Summarysupporting

confidence: 82%

Can the Superposition of Evaporative Flows Explain Broad Fe xxi Profiles during Solar Flares?

Polito

Testa

Pontieu

2019

ApJL

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“…Over the coalescing umbrae, where the composition deeper in the chromosphere is depleted of low-FIP elements prior to the flare, the bottom of flare loops will be filled with plasma of IFIP composition. The IFIP patches appear to last as long as either chromospheric evaporation is triggered by ionizing electron beams produced by magnetic field reconnection in the corona and/or thermal conduction of coronal plasma persists (Bagalá et al 1995;Cheung et al 2018). The only observations of high energy electrons of FL1 are from the Fermi Gamma-ray Space Telescope.…”

Section: Does Flaring Play a Role In Creating Ifip Bias Plasma?mentioning

confidence: 99%

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

Baker

Driel-Gesztelyi

Brooks

et al. 2019

ApJ

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Understanding elemental abundance variations in the solar corona provides an insight into how matter and energy flow from the chromosphere into the heliosphere. Observed variations depend on the first ionization potential (FIP) of the main elements of the Sun's atmosphere. High-FIP elements (>10 eV) maintain photospheric abundances in the corona, whereas low-FIP elements have enhanced abundances. Conversely, inverse FIP (IFIP) refers to the enhancement of high-FIP or depletion of low-FIP elements. We use spatially resolved spectroscopic observations, specifically the Ar XIV/Ca XIV intensity ratio, from Hinode's Extreme-ultraviolet Imaging Spectrometer to investigate the distribution and evolution of plasma composition within two confined flares in a newly emerging, highly sheared active region. During the decay phase of the first flare, patches above the flare ribbons evolve from the FIP to the IFIP effect, while the flaring loop tops show a stronger FIP effect. The patch and loop compositions then evolve toward the pre-flare basal state. We propose an explanation of how flaring in strands of highly sheared emerging magnetic fields can lead to flare-modulated IFIP plasma composition over coalescing umbrae which are crossed by flare ribbons. Subsurface reconnection between the coalescing umbrae leads to the depletion of low-FIP elements as a result of an increased wave flux from below. This material is evaporated when the flare ribbons cross the umbrae. Our results are consistent with the ponderomotive fractionation model (Laming 2015) for the creation of IFIP-biased plasma.

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“…Sample spectrograms are shown inFig. 2.Using a snapshot from a three-dimensional radiative MHD simulation of a solar flare(Cheung et al 2018), we synthesized the optically thin emergent EUV radiation using atomic models from theCHIANTI database (version 8 Del Zanna et al 2015). A spatial intensity image of the Fe XVI 264Å line is shown in panel (A) of Fig.…”

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confidence: 99%

Multi-component Decomposition of Astronomical Spectra by Compressed Sensing

Cheung

Pontieu

Martínez-Sykora

et al. 2019

ApJ

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The signal measured by an astronomical spectrometer may be due to radiation from a multi-component mixture of plasmas with a range of physical properties (e.g. temperature, Doppler velocity). Confusion between multiple components may be exacerbated if the spectrometer sensor is illuminated by overlapping spectra dispersed from different slits, with each slit being exposed to radiation from a different portion of an extended astrophysical object. We use a compressed sensing method to robustly retrieve the different components. This method can be adopted for a variety of spectrometer configurations, including single-slit, multi-slit (e.g., the proposed MUlti-slit Solar Explorer mission; MUSE) and slot spectrometers (which produce overlappograms).

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A comprehensive three-dimensional radiative magnetohydrodynamic simulation of a solar flare

Cited by 155 publications

References 50 publications

Can the Superposition of Evaporative Flows Explain Broad Fe xxi Profiles during Solar Flares?

Can the Superposition of Evaporative Flows Explain Broad Fe xxi Profiles during Solar Flares?

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

Multi-component Decomposition of Astronomical Spectra by Compressed Sensing

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