The Evolution of Plasma Composition during a Solar Flare

To, Andy S. H.; Long, David M.; Baker, D.; Brooks, David H.; Driel-Gesztelyi, L. van; Laming, J. Martin; Valori, G.

doi:10.3847/1538-4357/abe85a

Cited by 11 publications

(12 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to investigate the evolution of the coronal plasma composition, a suitable low-FIP and high-FIP spectral line pair must be identified among the available lines. Previous EIS composition studies have employed the Si X 258.38 Å/S X 264.22 Å line pair for 1-2 MK plasma (e.g., Brooks & Warren 2011;Baker et al 2013;Brooks et al 2015) and the Ca XIV 193.87 Å/Ar XIV 194.40 Å line pair for 3-4 MK plasmas (e.g., Doschek et al 2015;Baker et al 2020;To et al 2021). Neither of these well-known composition diagnostics is available in Study #180.…”

Section: Hinode/eis Observationsmentioning

confidence: 99%

Evolution of Plasma Composition in an Eruptive Flux Rope

Baker

Green

Brooks

et al. 2022

ApJ

Self Cite

View full text Add to dashboard Cite

Magnetic flux ropes are bundles of twisted magnetic field enveloping a central axis. They harbor free magnetic energy and can be progenitors of coronal mass ejections (CMEs). However, identifying flux ropes on the Sun can be challenging. One of the key coronal observables that has been shown to indicate the presence of a flux rope is a peculiar bright coronal structure called a sigmoid. In this work, we show Hinode EUV Imaging Spectrometer observations of sigmoidal active region (AR) 10977. We analyze the coronal plasma composition in the AR and its evolution as a sigmoid (flux rope) forms and erupts as a CME. Plasma with photospheric composition was observed in coronal loops close to the main polarity inversion line during episodes of significant flux cancellation, suggestive of the injection of photospheric plasma into these loops driven by photospheric flux cancellation. Concurrently, the increasingly sheared core field contained plasma with coronal composition. As flux cancellation decreased and a sigmoid/flux rope formed, the plasma evolved to an intermediate composition in between photospheric and typical AR coronal compositions. Finally, the flux rope contained predominantly photospheric plasma during and after a failed eruption preceding the CME. Hence, plasma composition observations of AR 10977 strongly support models of flux rope formation by photospheric flux cancellation forcing magnetic reconnection first at the photospheric level then at the coronal level.

show abstract

Section: Hinode/eis Observationsmentioning

confidence: 99%

Evolution of Plasma Composition in an Eruptive Flux Rope

Baker

Green

Brooks

et al. 2022

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…Observations by RESIK indicate that Ar is close to proxies of the photospheric abundance (Sylwester et al 2015;Lodders 2008). In the extreme ultraviolet, spectral and spatial flare observations include those made by the Extreme-ultraviolet Imaging Spectrometer instrument on the Japanese Hinode spacecraft (e.g., Brooks et al 2015;Doschek & Warren 2016Baker et al 2019;To et al 2021). These observations use the intensity ratio of a pair of Ca and Ar lines as a probe of the FIP effect, and show from maps of this ratio that the Ca line emission is enhanced in the main flare structures but in localised patches near sunspots the argon line emission is enhanced, giving rise to an inverse FIP effect (Doschek & Warren 2019).…”

Section: Introductionmentioning

confidence: 99%

New Solar Flare Calcium Abundances with No Surprises: Results from the Solar Maximum Mission Bent Crystal Spectrometer

Sylwester

Phillips

et al. 2022

ApJ

View full text Add to dashboard Cite

The calcium abundance in flare plasmas is estimated using X-ray spectra from the Solar Maximum Mission Bent Crystal Spectrometer (BCS) during the decays of 194 flares (Geostationary Operational Environmental Satellite, GOES, classifications from B6.4 to X13) occurring between 1980 and 1989. Previous work by Sylwester et al. found that the abundance varied from flare to flare. That analysis is improved on here using updated instrument parameters and by including all calcium lines viewed by the BCS instead of only the resonance line, so greatly enhancing the photon count statistics. The abundance variations are confirmed with the average abundance, A(Ca) (expressed logarithmically with A(H) = 12), equal to 6.77 ± 0.20 for 194 flares (141 of which are new in this study). This range corresponds to factors of between 1.7 and 7.2 larger than the photospheric abundance, and so our results are in line with a “first ionization potential” (FIP) effect whereby low-FIP elements like Ca (FIP = 6.11 eV) have enhanced coronal abundances. The Ca flare abundance is uncorrelated with solar activity indices, but weak correlations are suggested with GOES flare class and duration (larger A(Ca) for smaller and shorter flares). The ponderomotive force theory of Laming explaining the FIP effect gives a range of parameters within which our estimates of A(Ca) agree with the theory. However, this then gives rise to disagreements with previous estimates of the flare silicon and sulfur abundances, although those of argon and iron are in good agreement. Small adjustments of the theory may thus be necessary.

show abstract

“…The abundance ratios of Ne (highest FIP) to Fe (low FIP) can be order of 10 compared to the photospheric abundances of the Sun (Güdel 2007). An inverse FIP effect was also found for the Sun, for example, by Doschek et al (2015); Doschek & Warren (2016) when the analyzing of the spectra of calcium and argon lines, and recently by To et al (2021) from Hinode/Extreme-ultraviolet Imaging Spectrometer and by Katsuda et al (2020) for silicon, calcium, sulfur, and argon abundances determined for four solar flares of GOES X class. In all cases, the inverse FIP effect was only found during flares in small areas of very complex active regions.…”

Section: Introductionmentioning

confidence: 69%

On the Application of Differential Evolution to the Analysis of X-Ray Spectra

Kepa,

Sylwester,

Siarkowski

et al. 2022

Preprint

View full text Add to dashboard Cite

Using methods of differential evolution (DE,) we determined the coronal elemental abundances and the differential emission measure (DEM) distributions for the plasma flaring on 2003 January 21. The analyses have been based on RESIK X-ray spectra. DE belongs to the family of evolutionary algorithms. DE is conceptually simple and easy to be implemented, so it has been applied to solve many problems in science and engineering. In this study we apply this method in a new context: simultaneous determination of plasma composition and DEM . In order to increase the confidence in the results obtained using DE, we tested the use of its algorithms by comparing the DE synthesized spectra with respective spectra observed by RESIK. Extensive discussion of the DE method used and the obtained physical characteristics of flaring plasma is presented.

show abstract

The Evolution of Plasma Composition during a Solar Flare

Cited by 11 publications

References 66 publications

Evolution of Plasma Composition in an Eruptive Flux Rope

Evolution of Plasma Composition in an Eruptive Flux Rope

New Solar Flare Calcium Abundances with No Surprises: Results from the Solar Maximum Mission Bent Crystal Spectrometer

On the Application of Differential Evolution to the Analysis of X-Ray Spectra

Contact Info

Product

Resources

About