The study of umbral dots in sunspots based on SOT/Hinode observations

Ebadi, H.; Abbasvand, Vahid; Pourjavadi, H.

doi:10.1002/asna.201713311

Cited by 6 publications

(5 citation statements)

References 30 publications

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“…Umbral dots are the only candidate for this role. The size of umbral dots is of the same order as the size of local oscillation cells (Ebadi et al 2017;Goodarzi et al 2016). Besides, the umbral dots oscillate (Jess et al 2012;Krishna Prasad et al 2015;Chae et al 2017;Ebadi et al 2017).…”

Section: Local Oscillations and Umbral Dotsmentioning

confidence: 87%

“…The size of umbral dots are of the same order as the size of the local oscillation cells (Ebadi et al 2017;Goodarzi et al 2016). Besides, the umbral dots oscillate (Jess et al 2012;Prasad et al 2015;Chae et al 2017;Ebadi et al 2017). According to the current ideas, umbral dots originate due to convection in the sunspot magnetic field.…”

Section: Local Oscillations and Umbral Dotsmentioning

confidence: 99%

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Local sunspot oscillations and umbral dots

Zhugzhda

Сыч

2018

Res. Astron. Astrophys.

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Data analysis of sunspot oscillation based on 6-hr SDO run of observation showed that low frequency (0.2 < ω < 1mHz) oscillations are local similar to three and five minute oscillations. The oscillations in the sunspot are concentrated in cells of a few arcsec, each of which has its own oscillation spectrum. The analysis of two scenario for sunspot oscillations leads to conclusion that local sunspot oscillations occur due to subphotospheric resonator for slow mhd waves. Empirical models of sunspot atmosphere and the theory of slow waves in thin magnetic flux tubes is applied to the modeling of subphotospheric resonator. Spectrum of local oscillations consists of a great number of lines. This kind of spectrum can occur only if the subphospheric resonator is a magnetic tube with a rather weak magnetic field. Magnetic tubes of this sort are umbral dots that appear due to the convective tongues in the monolithic sunspots. The interrelation of local oscillations with umbral dots and wave fronts of traveling waves in sunspots is discussed.

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Section: Local Oscillations and Umbral Dotsmentioning

confidence: 87%

Section: Local Oscillations and Umbral Dotsmentioning

confidence: 99%

Local sunspot oscillations and umbral dots

Zhugzhda

Сыч

2018

Res. Astron. Astrophys.

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“…9, background). These bright sources are related to the so-called Umbral Dots (UDs) and widely investigated earlier in a number of papers (Jess et al 2012;Goodarzi et al 2016;Ebadi et al 2017). There are both as single UDs and UD chains.…”

Section: Photosphere Levelmentioning

confidence: 97%

“…But observations (Zhugzhda 1984;Settele et al 2001) questioned this hypothesis by taking into account the presence of local oscillations. The central problem was the presence of powerful local three-minute oscillations detected in the umbral dots at the photosphere level (Jess et al 2012;Ebadi et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Properties of Local Oscillations in the Lower Sunspot Atmosphere

Сыч

Zhugzhda

Yan

2020

ApJ

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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 combination of numerous independent oscillations located in the sources with small angular size. Their spatial shape varies from dots and cellular in the umbra to filaments in the penumbra. Each narrow spectrum harmonic corresponds to its source, without global correlation among themselves. There is weak background as low-frequency oscillation sources are distributed on whole umbra. At the photosphere level we found regions with co-phased broadband oscillations of the whole umbra. Their spectrum includes the ∼3-min harmonic, whose maximal value is localized in umbral dots (UDs), and the low frequency part near the ∼5-min period. It is shown that the oscillation sources are displaced at different heights with increasing angular size. We assume that the observed spatial distribution of wave sources indicates the existence a slow subphotosphere resonator with a vertical magnetic field in the umbra and wave cutoff frequency due to inclination of the magnetic field line in the penumbra.

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“…Second, the high-frequency intensity components were eliminated from the images by applying a Fast Fourier Transform (FFT) filter that removed brightness differences and errors caused by observational and atmospheric effects, following the methods used by (Watanabe, Kitai, and Ichimoto, 2009;Kilcik et al, 2012;Ebadi, Abbasvand, and Pourjavadi, 2017).…”

Section: Data Preparationmentioning

confidence: 99%

Relationships Between Physical Parameters of Umbral Dots Measured for 12 Sunspot Umbras with the Goode Solar Telescope

Calisir,

Yazici,

Kilcik

et al. 2023

Sol Phys

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We present a comprehensive analysis of the physical parameters and relationships of umbral dots (UDs), which assists in our understanding of the physical properties of the Sun. This study is based on a detailed analysis of UDs detected in 12 umbras belonging to 10 different sunspots using high-resolution data recorded by the Goode Solar Telescope at the Big Bear Solar Observatory. We obtained the physical parameters (brightness, diameter, eccentricity, lifetime, dynamic velocity) of each UD and calculated correlation coefficients using linear and nonlinear approaches to reveal the relationships between these parameters. We found that: i) the diameter of UDs are varying between 92.2 km to 246.5 km, the eccentricity varies between 0.02 to 0.65, the lifetime of UDs vary from 0.75 to 120.00 min and the dynamic velocities are varying from 0.01 km/s to 3.80 km/s. ii) The intensity-diameter and diameter-eccentricity show the highest degree of correlation, while the lowest linear correlation was obtained for the diameter-lifetime and the lowest nonlinear correlation was obtained for the eccentricity-lifetime relationships. iii) In general the nonlinear correlation coefficients are higher than the linear correlation without any exception. iv) The linear and nonlinear correlation coefficients are very close to each other in the case of diameter-eccentricity relation. v) While the average diameter, intensity, A. Kilcik

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The study of umbral dots in sunspots based on SOT/Hinode observations

Cited by 6 publications

References 30 publications

Local sunspot oscillations and umbral dots

Local sunspot oscillations and umbral dots

Properties of Local Oscillations in the Lower Sunspot Atmosphere

Relationships Between Physical Parameters of Umbral Dots Measured for 12 Sunspot Umbras with the Goode Solar Telescope

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