Studying Ca ii K Line Profile Shapes and Dynamic Processes in the Solar Chromosphere at the Base of a Coronal Hole

Grigoryeva, S. A.; Turova, I. P.; Ozhogina, O. A.

doi:10.1007/s11207-016-0951-9

Cited by 8 publications

(25 citation statements)

References 46 publications

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“…Further observations revealed, however, that, first, the periodicity of occurrence of the grains may have not only a three-minute range [Kalkofen, 1996;Lites et al, 1999;. In our previous work [Grigoryeva et al, 2016], we have also shown that K 2v grains have a complex spectral composition of oscillations. Second, the line profile variation may differ from the standard one.…”

Section: Parametersmentioning

confidence: 57%

“…Observation details and identification of chromospheric structures are described by Grigoryeva et al [2016].…”

Section: Observations and Their Processingmentioning

confidence: 99%

“…In our previous work [Grigoryeva et al, 2016], we have shown a large number of individual Ca II K pro-files observed in the chromospheric structures we selected (see Figure 4-7 [Grigoryeva et al, 2016]). We examined the profiles in a wavelength range =± 0.5 Å.…”

Section: Spatial and Temporal Variations Of Ca II K Line Profilesmentioning

confidence: 99%

“…Special attention should be paid to the profile which is observed in the area of low brightness "p1". We have already written about profiles of this area in our previ-ous work [Grigoryeva et al, 2016], where we also discussed reversal-free profiles, which occurred in the "c" and "x" structures. The reversal-free profiles have been examined in detail in .…”

Section: Parametersmentioning

confidence: 99%

“…Of interest here are the results that can confirm the previously obtained results and add confidence in the reliability of the latter. This paper is a sequel to [Grigoryeva et al, 2016]. The authors have examined Ca II lines, using observations of two regions located at the base of a coronal hole.…”

Section: Introductionmentioning

confidence: 99%

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Spatial and temporal variations of K Ca II line profile shapes in different structures of the solar chromosphere. I. Features of individual profiles

Turova¹,

Grigor'eva²,

Grigoryeva

et al. 2018

Solar-Terrestrial Physics

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We have studied Ca II K line profiles, using two time series of spectrograms taken in two regions near the solar disk center. In each of the regions, the spectrograph slit cut out several areas of the quiet region and a plage. For the selected chromospheric structures, we have derived K line profiles and have defined a number of parameters that characterize the spatial and temporal variations of the profiles. The analysis of profile shapes in different structures belonging to the same moment of time has shown that there are structures whose profiles differ only slightly from each other in the photosphere, but differ dramatically in the chromosphere. The structures begin to differ from the level of formation of K 1 and continue to differ further in the chromosphere. There are, however, structures which begin to differ at the level of the photosphere and continue to differ in the chromosphere. The difference between profile shapes in different structures is likely to be associated both with different thermodynamic conditions and with different magnetic field topology at a given point at a given time. We have examined temporal variations of the Ca II K line profiles in structural chromospheric elements, which are caused by the process of K 2v grains. In most of the studied areas of the chromospheric structures, the brightening of the K 2v peak develops according to the "common" scenario: at the time of maximum brightness, the line shifts toward the red side. There are, however, cases when the brightening of the K 2v peak occurs with a shift of the line to the violet side or with no shift at all. We have constructed scatter plots for some pairs of profile parameters related to intensities at characteristic points of the profile and their shifts. A correlation has been found between intensities in the center and wings of the K line. The correlation between shifts of the K 2v and K 2r peaks is very weak or completely absent.

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Section: Parametersmentioning

confidence: 57%

“…Observation details and identification of chromospheric structures are described by Grigoryeva et al [2016].…”

Section: Observations and Their Processingmentioning

confidence: 99%

Section: Spatial and Temporal Variations Of Ca II K Line Profilesmentioning

confidence: 99%

Section: Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Spatial and temporal variations of K Ca II line profile shapes in different structures of the solar chromosphere. I. Features of individual profiles

Turova¹,

Grigor'eva²,

Grigoryeva

et al. 2018

Solar-Terrestrial Physics

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Propagating Oscillations in the Lower Atmosphere Under Coronal Holes

et al. 2021

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The subject of this study is oscillations in the lower atmosphere in coronal-hole regions, where the conditions are favorable for propagation between the atmospheric layers. Based on spectroscopic observations in photospheric and chromospheric lines, we analyzed the features of the oscillations that show signs of propagation between the layers of the solar atmosphere. Using the cross-spectrum wavelet algorithm, we found that both chromospheric and photospheric signals under coronal holes share a range of significant oscillations with periods around five minutes, while the signals outside coronal holes show no mutual oscillations in the photosphere and chromosphere. The phase shift between the layers indicates a predominantly upward propagation with partial presence of standing waves. We have also tested the assumption that the torsional Alfvén waves propagating in the corona originate in the lower atmosphere. However, the observed line-width oscillations, although similar in period to the Alfvén waves observed earlier in the corona of open-field regions, seem to be associated with other magnetohydrodynamic (MHD) modes. If we assume that the oscillations that we observed are related to Alfvén waves, then perhaps this is only through the mechanisms of the slow-MHD-wave transformation.

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SPATIAL AND TEMPORAL VARIATIONS OF K Ca II LINE PROFILE SHAPES IN DIFFERENT STRUCTURES OF THE SOLAR CHROMOSPHERE. II. DETERMINATION TECHNIQUE AND CORRELATION RELATIONSHIPS BETWEEN THE K CA II LINE PARAMETERS FOR K1 AND K2 FEATURES

Turova

Grigoryeva

Ozhogina

2020

Solar-Terrestrial Physics

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We have studied two regions located at the base of a coronal hole. For the K₁ intensity minima and K₂ peaks, which form between the upper photosphere and the lower chromosphere and in the lower chromosphere respectively, a number of Ca II line parameters have been computed. We have improved the determination technique for ∆λᴋ₁ᵥ and ∆λᴋ₁ᵣ, ∆λᴋ₂ᵥ and ∆λᴋ₂ᵣ line profile shifts, including certain cases when their direct determination was complicated. We have determined Iᴋ₁ᵥ, Iᴋ₁ᵣ, Iᴋ₂ᵥ, Iᴋ₂ᵣ intensities, K₁ minima and K₂ peaks separations SEPᴋ₁ = ∆λᴋ₁ᵣ – ∆λᴋ₁ᵥ, SEPᴋ₂ = ∆λᴋ₂ᵣ – ∆λᴋ₂ᵥ, respectively. We have constructed scatter plots and have computed correlation relationships between parameters relating to different levels of atmosphere. We have obtained the following results. The intensities observed in the lower and middle chromosphere are connected closer than intensities related to the upper photosphere and middle chromosphere. The structures with a stronger magnetic field are brighter at the upper photosphere and lower chromosphere levels as compared to the structures with a weaker magnetic field. K₁ minima separations are of greater value for the structures with a stronger magnetic field relative to the structures with a weaker magnetic field, whereas K₂ peaks separations demonstrate the opposite behavior. They are lower for the structures with a stronger magnetic field. It is true not only for the chosen structures belonging to quiet regions but also for the plage, though we need additional statistics for plages. The relation between shifts of K₁ minima and K₂ peak intensities for violet and red wings appeared to be weak. This may be due to the considerable contribution of random movements to the velocity field at the upper photosphere and lower chromosphere levels or due to different forming levels for the profile violet and red wings.

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Studying Ca ii K Line Profile Shapes and Dynamic Processes in the Solar Chromosphere at the Base of a Coronal Hole

Cited by 8 publications

References 46 publications

Spatial and temporal variations of K Ca II line profile shapes in different structures of the solar chromosphere. I. Features of individual profiles

Spatial and temporal variations of K Ca II line profile shapes in different structures of the solar chromosphere. I. Features of individual profiles

Propagating Oscillations in the Lower Atmosphere Under Coronal Holes

SPATIAL AND TEMPORAL VARIATIONS OF K Ca II LINE PROFILE SHAPES IN DIFFERENT STRUCTURES OF THE SOLAR CHROMOSPHERE. II. DETERMINATION TECHNIQUE AND CORRELATION RELATIONSHIPS BETWEEN THE K CA II LINE PARAMETERS FOR K1 AND K2 FEATURES

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