Dependence of sunspot photospheric waves on the depth of the source of solar<i>p</i>-modes

Felipe, T.; Khomenko, E.

doi:10.1051/0004-6361/201630123

Cited by 14 publications

(15 citation statements)

References 36 publications

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“…In addition, we assume that the driving source of the wave is located below the photosphere inside the flux tube. This approach is in line with the suggestion of Zhao et al (2015) and Felipe & Khomenko (2017) made to interpret the photospheric fast-moving radial wave patterns. In this scenario a fast mode wave is driven at the high-β region, then it propagates quasi-isotropically to the β = 1 layer (see Figure 2).…”

Section: Observationsupporting

confidence: 89%

“…The internal excitation was further supported by Cho et al (2019)'s identification of several patterns characterized by oscillation centers and radial propagation above individual umbral dots that are under substantial changes. Recent works suggested that an internal driving source may be located, below the sunspot photosphere down to 5 Mm in the sunspot's flux tube, by analyzing the photospheric fast-moving wave patterns (Zhao et al 2015;Felipe & Khomenko 2017).…”

Section: Introductionmentioning

confidence: 99%

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The Physical Nature of Spiral Wave Patterns in Sunspots

Kang

Chae

Nakariakov

et al. 2019

ApJL

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Recently, spiral wave patterns (SWPs) have been detected in 3 minute oscillations of sunspot umbrae, but the nature of this phenomenon has remained elusive. We present a theoretical model that interprets the observed SWPs as the superposition of two different azimuthal modes of slow magnetoacoustic waves driven below the surface in an untwisted and non-rotating magnetic cylinder. We apply this model to SWPs of the line-of-sight (LOS) velocity in a pore observed by the Fast Imaging Solar Spectrograph installed at the 1.6 m Goode Solar Telescope. One-and two-armed SWPs were identified in instantaneous amplitudes of LOS Doppler velocity maps of 3 minute oscillations. The associated oscillation periods are about 160 s, and the durations are about 5 minutes. In our theoretical model, the observed spiral structures are explained by the superposition of non-zero azimuthal modes driven 1600 km below the photosphere in the pore. The one-armed SWP is produced by the slow-body sausage (m = 0) and kink (m = 1) modes, and the two-armed SWP is formed by the slow-body sausage (m = 0) and fluting (m = 2) modes of the magnetic flux tube forming the pore.

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Section: Observationsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

The Physical Nature of Spiral Wave Patterns in Sunspots

Kang

Chae

Nakariakov

et al. 2019

ApJL

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“…They conjectured that a disturbance occurring at about 5000 km under the sunspot surface from the MHD sunspot model and the ray-path approximation with magnetic fields. Felipe & Khomenko (2017) performed MHD numerical simulations to confirm the dependence of the source depth. They concluded that the measured horizontal fast-moving waves consistent with waves generated between about 1000 km and 5000 km beneath the sunspot photosphere.…”

Section: Discussionmentioning

confidence: 99%

Source Depth of Three-minute Umbral Oscillations

Cho

Chae

2020

ApJL

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We infer the depth of the internal sources giving rise to three-minute umbral oscillations. Recent observations of ripple-like velocity patterns of umbral oscillations supported the notion that there exist internal sources exciting the umbral oscillations. We adopt the hypothesis that the fast magnetohydrodynamic (MHD) waves generated at a source below the photospheric layer propagate along different paths, reach the surface at different times, and excited slow MHD waves by mode conversion. These slow MHD waves are observed as the ripples that apparently propagate horizontally. The propagation distance of the ripple given as a function of time is strongly related to the depth of the source. Using the spectral data of the Fe i 5435Å line taken by the Fast Imaging Solar Spectrograph of the Goode Solar Telescope at Big Bear Solar Observatory, we identified five ripples and determined the propagation distance as a function of time in each ripple. From the model fitting to these data, we obtained the depth between 1000 km and 2000 km. Our result will serve as an observational constraint to understanding the detailed processes of magnetoconvection and wave generation in sunspots.

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“…The detection of the fast-traveling waves in the frequency range of 2.5 -4.0 mHz around sunspots with estimated source location approximately 5 Mm beneath a sunspot (Zhao et al 2015) recently was supported by the simulations of Felipe & Khomenko (2017) who performed a parametric study by placing artificial localized sources at various depths and compared the surface wave speed with the observations. However, due to uncertainty of the helioseismology analysis, the location of the acoustic sources relative to the subsurface magnetic structure, as well as the mechanism of wave excitation in the deep layers, remained unclear.…”

Section: Introductionmentioning

confidence: 94%

The Origin of Deep Acoustic Sources Associated with Solar Magnetic Structures

Kitiashvili

Kosovichev

Mansour

et al. 2019

ApJ

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It is generally accepted that solar acoustic (p) modes are excited by nearsurface turbulent motions, in particular, by downdrafts and interacting vortices in intergranular lanes. Recent analysis of Solar Dynamics Observatory data by Zhao et al. (2015) revealed fast-moving waves around sunspots, which are consistent with magnetoacoustic waves excited approximately 5 Mm beneath the sunspot. We analyzed 3D radiative MHD simulations of solar magnetoconvection with a self-organized pore-like magnetic structure, and identified more than 600 individual acoustic events both inside and outside of this structure. By performing a case-by-case study, we found that surrounding the magnetic structure, acoustic sources are associated with downdrafts. Their depth correlates with downdraft speed and magnetic fields. The sources often can be transported into deeper layers by downdrafts. The wave front shape, in the case of a strong or inclined downdraft, can be stretched along the downdraft. Inside the magnetic structure, excitation of acoustic waves is driven by converging flows. Frequently, strong converging plasma streams hit the structure boundaries, causing compressions in its interior that excite acoustic waves. Analysis of the depth distribution of acoustic events shows the strongest concentration at 0.2 -1 Mm beneath the surface for the outside sources and 2.5 -3 Mm for the excitation event inside the structure.

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Dependence of sunspot photospheric waves on the depth of the source of solarp-modes

Cited by 14 publications

References 36 publications

The Physical Nature of Spiral Wave Patterns in Sunspots

The Physical Nature of Spiral Wave Patterns in Sunspots

Source Depth of Three-minute Umbral Oscillations

The Origin of Deep Acoustic Sources Associated with Solar Magnetic Structures

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