Internal Fine Structure of Ellerman Bombs

Hashimoto, Yuki; Kitai, Reizaburo; Ichimoto, Kiyoshi; Ueno, S.; Nagata, Shinji; Ishii, Takako T.; Hagino, M.; Komori, Hiroyuki; Nishida, Keisuke; Matsumoto, Takuma; Otsuji, Kenichi; Nakamura, Tahei; Kawate, Tomoko; Watanabe, Hiroko; Shibata, Kazunari

doi:10.1093/pasj/62.4.879

Cited by 44 publications

(43 citation statements)

References 23 publications

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“…In both lines the slab is thick for the target parameters, but overlying cooler fibrils are yet thicker so that only wing brightenings result, at smaller moustache extent then for Hα since these lines suffer no A124, page 10 of 13 Stark broadening. This is also conform observations (Paper II for Ca ii 8542 Å, Hashimoto et al 2010 for Ca ii H).…”

Section: Lte Extinction Of Eb Diagnosticssupporting

confidence: 93%

“…In the outer Hα wings surrounding cool gas lacks moustache opacity from shortage of free electrons for Stark broadening. The therefore unmolested Hα-moustache sharpness permits, at sufficiently high angular resolution, to resolve very fine substructure within EBs, as observed in Hashimoto et al (2010) and Paper I.…”

Section: Lte Extinction Of Eb Diagnosticsmentioning

confidence: 89%

“…In addition, other lines such as Ca ii H and Ca ii 8542 Å do show EB moustaches but less wide than Hα (Hashimoto et al 2010;R. Rezaei, priv.…”

Section: Hα Extinction In Ltementioning

confidence: 99%

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Hαfeatures with hot onsets

Rutten

2016

A&A

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Ellerman bombs are transient brightenings of the wings of the Balmer lines that uniquely mark reconnection in the solar photosphere.They are also bright in strong Ca ii and ultraviolet lines and in ultraviolet continua, but they are not visible in the optical continuum and the Na i D and Mg i b lines. These discordant visibilities invalidate all published Ellerman bomb modeling. I argue that the assumption of Saha-Boltzmann lower-level populations is informative to estimate bomb-onset opacities for these diverse diagnostics, even and especially for Hα, and employ such estimates to gauge the visibilities of Ellerman bomb onsets in all of them. They constrain Ellerman bomb formation to temperatures 10 000−20 000 K and hydrogen densities around 10 15 cm −3 . Similar arguments likely hold for Hα visibility in other transient phenomena with hot and dense onsets.

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Section: Lte Extinction Of Eb Diagnosticssupporting

confidence: 93%

Section: Lte Extinction Of Eb Diagnosticsmentioning

confidence: 89%

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Hαfeatures with hot onsets

Rutten

2016

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“…Ellerman bombs have been observed in the Ca ii H line by Hashimoto et al (2010). We probe the diagnostic potential of the Ca ii H line profile to identify and study EBs.…”

Section: Caii H Line: An Ideal Tracer Of Ebsmentioning

confidence: 96%

“…These studies showed that EBs exhibit enhanced brightenings not only in the wing of the Hα line, but also in the wings of the Ca ii IR line. Traces of EBs were also observed in the ultraviolet (UV) continuum at 160 nm (Qiu et al 2000;Pariat et al 2007), while Hashimoto et al (2010) observed EBs in the Ca ii H line.…”

Section: Introductionmentioning

confidence: 96%

Multiwavelength spectropolarimetric observations of an Ellerman bomb

Rezaei

Beck

2015

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Context. Ellerman bombs (EBs) are enhanced emission in the wings of the Hα line in the solar spectrum. Aims. We study the structure of an EB in the photosphere and chromosphere.Methods. We analyze simultaneous observations of four chromospheric lines (Hα, Ca ii H, Ca ii IR 854 nm, and He i 1083 nm) as well as two photospheric lines (Fe i 630 and Si i 1082.7 nm) along with high-cadence 160 and 170 nm ultraviolet (UV) continuum filtergrams. Full Stokes data from the Helioseismic and Magnetic Imager (HMI) are used to trace the temporal evolution of the magnetic structure.Results. We identify the EB by excess emission in the wings of the Hα line, a brightening in the UV continuum, and large emission peaks in the core of the two Ca ii lines. The EB shows a blueshift in all chromospheric lines, while no shifts are observed in the photospheric lines. The blueshift in the chromospheric layer causes very asymmetric emission peaks in the Ca ii H line. The photospheric Si i spectral line shows a shallower line depth at the location of the EB. The UV continuum maps show that the EB was substantially brighter than its surroundings for about 30 min. The continuum contrast of the EB from 170 nm to 1080 nm shows a power-law dependency on the wavelength. The temperature enhancement amounts to 130 K in the low photosphere and 400 K at the temperature minimum level. This temperature excess is also seen in an LTE inversion of the Ca ii spectra. The total thermal and radiative energy content of the EB is about 10 20 J and 10 18 J in the photosphere and chromosphere, respectively. The HMI data hints at a photospheric magnetic flux cancellation as the driver of the EB. Conclusions. Ellerman bombs release the energy in a height range of several pressure scale heights around the temperature minimum such that they affect both the photosphere and the lower chromosphere.

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Solar Ultraviolet Bursts

et al. 2018

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The term "ultraviolet (UV) burst" is introduced to describe small, intense, transient brightenings in ultraviolet images of solar active regions. We inventorize their properties and provide a definition based on image sequences in transition-region lines. Coronal signatures are rare, and most bursts are associated with small-scale, canceling oppositepolarity fields in the photosphere that occur in emerging flux regions, moving magnetic features in sunspot moats, and sunspot light bridges. We also compare UV bursts with similar transition-region phenomena found previously in solar ultraviolet spectrometry and with similar phenomena at optical wavelengths, in particular Ellerman bombs. Akin to the lat-Electronic supplementary material The online version of this article (https://doi.

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Internal Fine Structure of Ellerman Bombs

Cited by 44 publications

References 23 publications

Hαfeatures with hot onsets

Hαfeatures with hot onsets

Multiwavelength spectropolarimetric observations of an Ellerman bomb

Solar Ultraviolet Bursts

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