Abstract:We present a study of wave processes in the sunspot region NOAA 12670 on 2017 August 10 observed by the Goode Solar Telescope in the TiO 7057Å and Hα 6563Å spectral lines. To study the distribution of power oscillations and their dynamics, we applied the pixelized wavelet filtering (PWF) technique. For the first time, the spatial structure of oscillation sources as a footpoints of fine magnetic tubes, anchored in the sunspot umbra was obtained. We found that at the chromosphere level, emission variation is a c… Show more
“…The fine structure of spectrum as width between peaks does not exceed approximately 0.1 mHz, which is consistent with previously obtained results [45] sources inside the umbra. It can be assumed [9] that each source is associated with a separate harmonic of the spectrum. We found a compact pulsating source near the centre of the umbra, where spherical waves begin to propagate.…”
Section: Results and Discussion (A) Temporal Dynamics Of The 3-min Brmentioning
confidence: 99%
“…The power of the oscillations in the approximately 3-min window (figure 2 f ) shows a thin spatial structure representative of elongated and localized sources inside the umbra. It can be assumed [9] that each source is associated with a separate harmonic of the spectrum. Figure 3Snapshots of the approximately 3-min broadband wavefronts propagating in the SDO/AIA 304 Å channel from 00:12:57 to 00:14:57 UT (upper panels) and from 00:48:09 to 00:50:09 UT (lower panels) with a 24 s cadence.…”
Section: Resultsmentioning
confidence: 99%
“…To search for propagating waves in the sunspot and recover their temporal dynamics, we employed a pixelized wavelet filtering (PWF) technique [35], which is widely used for studying oscillations in coronal loops [37,38] and determining the fine spatial structure of wave sources in sunspots [9]. This technique is a generalization of the wavelet transform techniques applied to image cubes.…”
Section: (A) Methods Of Pixelized Mode Decompositionmentioning
confidence: 99%
“…Oscillation sources with periods less than approximately 3 min are localized in the umbra and reduce in physical size as the period decreases [6][7][8]. In the central part of the umbra, the footpoints of thin magnetic tubes appear in the form of oscillating cells and dots [9]. One of the main physical mechanisms that determines the oscillatory power in the umbral core is related to the resonant cavity trapped between the photosphere and chromosphere [10,11].…”
Section: Introductionmentioning
confidence: 99%
“…Local UFs are, by definition, localized near the footpoints of thin magnetic waveguides, anchored in the umbra. Recently, it was shown that in the chromosphere the umbral oscillations are a collection of large independent oscillations located in isolated sources with small angular size [24], resulting in their spatial structure changing from cellular pockets at the umbral centre through to filamentary features at the outer edge of the sunspot periphery. Each narrow harmonic of the corresponding spectrum relates to a source that is connected to a separate magnetic flux tube anchored in the umbra.…”
We present a study of wave processes occurring in solar active region NOAA 11131 on 10 December 2010, captured by the Solar Dynamics Observatory in the 1600 Å, 304 Å and 171 Å channels. For spectral analysis, we employed pixelized wavelet filtering together with a developed digital technique based on empirical mode decomposition. We studied the ∼3-minute wave dynamics to obtain relationships with the magnetic structuring of the underlying sunspot. We found that during development of wave trains the motion path occurred along a preferential direction, and that the broadband wavefronts can be represented as a set of separate narrowband oscillation sources. These sources become visible as the waves pass through the umbral inhomogeneities caused by the differing magnetic field inclination angles. We found the spatial and frequency fragmentation of wavefronts, and deduced that the combination of narrowband spherical and linear parts of the wavefronts provide the observed spirality. Maps of the magnetic field inclination angles confirm this assumption. We detect the activation of umbral structures as the increasing of oscillations in the sources along the front ridge. Their temporal dynamics are associated with the occurrence of umbral flashes. Spatial localization of the sources is stable over time and depends on the oscillation period. We propose that these sources are the result of wave paths along the loops extending outwards from the magnetic bundles of the umbra.
This article is part of the Theo Murphy meeting issue ‘High-resolution wave dynamics in the lower solar atmosphere’.
“…The fine structure of spectrum as width between peaks does not exceed approximately 0.1 mHz, which is consistent with previously obtained results [45] sources inside the umbra. It can be assumed [9] that each source is associated with a separate harmonic of the spectrum. We found a compact pulsating source near the centre of the umbra, where spherical waves begin to propagate.…”
Section: Results and Discussion (A) Temporal Dynamics Of The 3-min Brmentioning
confidence: 99%
“…The power of the oscillations in the approximately 3-min window (figure 2 f ) shows a thin spatial structure representative of elongated and localized sources inside the umbra. It can be assumed [9] that each source is associated with a separate harmonic of the spectrum. Figure 3Snapshots of the approximately 3-min broadband wavefronts propagating in the SDO/AIA 304 Å channel from 00:12:57 to 00:14:57 UT (upper panels) and from 00:48:09 to 00:50:09 UT (lower panels) with a 24 s cadence.…”
Section: Resultsmentioning
confidence: 99%
“…To search for propagating waves in the sunspot and recover their temporal dynamics, we employed a pixelized wavelet filtering (PWF) technique [35], which is widely used for studying oscillations in coronal loops [37,38] and determining the fine spatial structure of wave sources in sunspots [9]. This technique is a generalization of the wavelet transform techniques applied to image cubes.…”
Section: (A) Methods Of Pixelized Mode Decompositionmentioning
confidence: 99%
“…Oscillation sources with periods less than approximately 3 min are localized in the umbra and reduce in physical size as the period decreases [6][7][8]. In the central part of the umbra, the footpoints of thin magnetic tubes appear in the form of oscillating cells and dots [9]. One of the main physical mechanisms that determines the oscillatory power in the umbral core is related to the resonant cavity trapped between the photosphere and chromosphere [10,11].…”
Section: Introductionmentioning
confidence: 99%
“…Local UFs are, by definition, localized near the footpoints of thin magnetic waveguides, anchored in the umbra. Recently, it was shown that in the chromosphere the umbral oscillations are a collection of large independent oscillations located in isolated sources with small angular size [24], resulting in their spatial structure changing from cellular pockets at the umbral centre through to filamentary features at the outer edge of the sunspot periphery. Each narrow harmonic of the corresponding spectrum relates to a source that is connected to a separate magnetic flux tube anchored in the umbra.…”
We present a study of wave processes occurring in solar active region NOAA 11131 on 10 December 2010, captured by the Solar Dynamics Observatory in the 1600 Å, 304 Å and 171 Å channels. For spectral analysis, we employed pixelized wavelet filtering together with a developed digital technique based on empirical mode decomposition. We studied the ∼3-minute wave dynamics to obtain relationships with the magnetic structuring of the underlying sunspot. We found that during development of wave trains the motion path occurred along a preferential direction, and that the broadband wavefronts can be represented as a set of separate narrowband oscillation sources. These sources become visible as the waves pass through the umbral inhomogeneities caused by the differing magnetic field inclination angles. We found the spatial and frequency fragmentation of wavefronts, and deduced that the combination of narrowband spherical and linear parts of the wavefronts provide the observed spirality. Maps of the magnetic field inclination angles confirm this assumption. We detect the activation of umbral structures as the increasing of oscillations in the sources along the front ridge. Their temporal dynamics are associated with the occurrence of umbral flashes. Spatial localization of the sources is stable over time and depends on the oscillation period. We propose that these sources are the result of wave paths along the loops extending outwards from the magnetic bundles of the umbra.
This article is part of the Theo Murphy meeting issue ‘High-resolution wave dynamics in the lower solar atmosphere’.
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