FISS Observations of Vertical Motion of Plasma in Tiny Pores

Cho, K.-S.; Bong, Su-Chan; Chae, Jongchul; Kim, Y.-H.; Park, Y.-D.; Katsukawa, Y.

doi:10.1007/s11207-012-0196-1

Cited by 11 publications

(10 citation statements)

References 27 publications

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“…As can be seen from the bi-sector velocities, which best represent lower atmospheric heights, a global upflow with an average velocity of ∼8 km s −1 is present, with a peak value approaching 14 km s −1 recorded. The observed decrease in the plasma upflow velocities towards the Ca II line core remains consistent with the previous work of Cho et al (2013). With the addition of a bulk plasma upflow, the initial speed calculated can be considered as a Doppler-shifted phase speed, which incorporates both the phase velocity of the wave and the bulk motion of the transfer medium.…”

Section: Oscillations In the Pore Intensitysupporting

confidence: 89%

Wave Damping Observed in Upwardly Propagating Sausage-Mode Oscillations Contained Within a Magnetic Pore

Grant

Jess

Moreels

et al. 2015

ApJ

136

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We present observational evidence of compressible magnetohydrodynamic wave modes propagating from the solar photosphere through to the base of the transition region in a solar magnetic pore. High cadence images were obtained simultaneously across four wavelength bands using the Dunn Solar Telescope. Employing Fourier and wavelet techniques, sausage-mode oscillations displaying significant power were detected in both intensity and area fluctuations. The intensity and area fluctuations exhibit a range of periods from 181 − 412 s, with an average period ∼290 s, consistent with the global p-mode spectrum. Intensity and area oscillations present in adjacent bandpasses were found to be out-of-phase with one another, displaying phase angles of 6.12 • , 5.82 • and 15.97 • between 4170Å continuum -G-band, G-band -Na I D 1 and Na I D 1 -Ca II K heights, respectively, reiterating the presence of upwardly-propagating sausage-mode waves. A phase relationship of ∼0 • between same-bandpass emission and area perturbations of the pore best categorises the waves as belonging to the 'slow' regime of a dispersion diagram. Theoretical calculations reveal that the waves are surface modes, with initial photospheric energies in excess of 35 000 W m −2 . The wave energetics indicate a substantial decrease in energy with atmospheric height, confirming that magnetic pores are able to transport waves that exhibit appreciable energy damping, which may release considerable energy into the local chromospheric plasma.

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Section: Oscillations In the Pore Intensitysupporting

confidence: 89%

Wave Damping Observed in Upwardly Propagating Sausage-Mode Oscillations Contained Within a Magnetic Pore

Grant

Jess

Moreels

et al. 2015

ApJ

136

View full text Add to dashboard Cite

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“…As solar pores are good wave guides, it is valid to assume that only the pore itself may be driven. Numerical simulations (Cameron et al 2007) supported by observations (Cho et al 2013) suggest that rapid cooling within pores could lead to downflows that collide with the plasma of lower layers to produce rebounding upflows, which further motivates the assumption of a localized driver. Moreover, previous simulations (Kato et al 2016) show that photospheric buffeting by turbulent motions lead to the efficient excitation of waves.…”

Section: Localized Drivermentioning

confidence: 92%

Finding the mechanism of wave energy flux damping in solar pores using numerical simulations

Riedl

Gilchrist-Millar

Doorsselaere

et al. 2021

A&A

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Context. Solar magnetic pores are, due to their concentrated magnetic fields, suitable guides for magnetoacoustic waves. Recent observations have shown that propagating energy flux in pores is subject to strong damping with height; however, the reason is still unclear. Aims. We investigate possible damping mechanisms numerically to explain the observations. Methods. We performed 2D numerical magnetohydrodynamic (MHD) simulations, starting from an equilibrium model of a single pore inspired by the observed properties. Energy was inserted into the bottom of the domain via different vertical drivers with a period of 30 s. Simulations were performed with both ideal MHD and non-ideal effects. Results. While the analysis of the energy flux for ideal and non-ideal MHD simulations with a plane driver cannot reproduce the observed damping, the numerically predicted damping for a localized driver closely corresponds with the observations. The strong damping in simulations with localized driver was caused by two geometric effects, geometric spreading due to diverging field lines and lateral wave leakage.

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“…FISS is an imaging spectrograph that adopts an Echelle disperser with field-scanning method, with which twodimensional spectra and images of dual spectral bands (Hα and Ca II 8542 Å) can be acquired simultaneously (Chae et al 2013a). FISS can probe into the physical processes in the photosphere and chromosphere, including plasma flows and oscillations in various phenomena, like fibrils, prominence, and EBs (Anđić et al 2013;Chae et al 2013b;Cho et al 2013;Maurya et al 2013;Park et al 2013;Yang et al 2013). Using FISS, we obtained Hα and Ca II 8542 Å spectra with high spatial and spectral resolution for a target area near the pores in NOAA 11765 on 2013 June 6.…”

Section: Observationsmentioning

confidence: 99%

Spectral Observations of Ellerman Bombs and Fitting With a Two-Cloud Model

Hong

Ding

et al. 2014

ApJ

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We study the Hα and Ca II 8542 Å line spectra of four typical Ellerman bombs (EBs) in active region NOAA 11765 on 2013 June 6, observed with the Fast Imaging Solar Spectrograph installed at the 1.6 meter New Solar Telescope at Big Bear Solar Observatory. Considering that EBs may occur in a restricted region in the lower atmosphere, and that their spectral lines show particular features, we propose a two-cloud model to fit the observed line profiles. The lower cloud can account for the wing emission, and the upper cloud is mainly responsible for the absorption at line center. After choosing carefully the free parameters, we get satisfactory fitting results. As expected, the lower cloud shows an increase of the source function, corresponding to a temperature increase of 400-1000 K in EBs relative to the quiet Sun. This is consistent with previous results deduced from semi-empirical models and confirms that a local heating occurs in the lower atmosphere during the appearance of EBs. We also find that the optical depths can increase to some extent in both the lower and upper clouds, which may result from either a direct heating in the lower cloud, or illumination by an enhanced radiation on the upper cloud. The velocities derived from this method, however, are different from those obtained using the traditional bisector method, implying that one should be cautious when interpreting this parameter. The two-cloud model can thus be used as an efficient method to deduce the basic physical parameters of EBs.

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FISS Observations of Vertical Motion of Plasma in Tiny Pores

Cited by 11 publications

References 27 publications

Wave Damping Observed in Upwardly Propagating Sausage-Mode Oscillations Contained Within a Magnetic Pore

Wave Damping Observed in Upwardly Propagating Sausage-Mode Oscillations Contained Within a Magnetic Pore

Finding the mechanism of wave energy flux damping in solar pores using numerical simulations

Spectral Observations of Ellerman Bombs and Fitting With a Two-Cloud Model

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