Study of the Magnetic Properties of Sunspot Umbrae

Zagainova, Yu. S.; Файнштейн, В. Г.; Обридко, В. Н.; Rudenko, G. V.

doi:10.1134/s1063772922030064

Cited by 5 publications

(1 citation statement)

References 77 publications

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“…However, the direct formation of sunspots and active regions in general takes place directly near the photosphere, probably in the leptocline (see Kosovichev and Rozelot, 2018, for definition). An analysis of the emergence of an active region was studied in the works of Getling, Ishikawa, and Buchnev (2016); Getling and Buchnev (2019); Zagainova et al (2022). The early stage of AR formation includes the floating up of a new magnetic flux in the form of a chaotic mixture of magnetic elements of different polarity (Smirnova et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

Temporal and Periodic Analysis of Penumbra-Umbra Ratio for the Last Four Solar Cycles

Chowdhury

Kılçık

Saha

et al. 2023

Preprint

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We investigate the long-term dynamic behavior of the sunspot penum8bra to umbra area ratio by analyzing the Debrecen Photoheliographic Data9 (DPD) of sunspot groups during the period 1976–2017 (Solar Cycles 21-24). We consider all types of spots and notice that the average penumbra-umbra ratio does not exhibit any significant variation with spot latitudes, solar cycle phases as well as sunspot cycle strengths. However, the behavior of this ratio is different when we consider the latitudinal distribution of the northern and southern hemisphere separately. Our analysis indicates that the average spot ratio varies from 5.5 to 6.5 and for very large sunspots (> 5000 μhem; one μhem is 10-6 the area of millionth of visual solar hemisphere) its value rises to about 8.3. Further, we found that this ratio exhibit some kind of solar cycle trend for both smaller (area <100 μhem) and large (area > 100 μhem) sunspots. Finally, we have studied the periodic and quasi-periodic variations present in this ratio time series by the multitaper method (MTM) and wavelet technique. We found that along with the ∼11-years (solar cycle period), the penumbra to umbra area ratio data also show several mid-term variations, specifically, Rieger type and quasi-biennial periodicities.We also found that the Rieger-type of periods occurs in all cycles, but the temporal evolution and the modulation of these types of periodicities are different in different solar cycles.

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Section: Discussionmentioning

confidence: 99%

Temporal and Periodic Analysis of Penumbra-Umbra Ratio for the Last Four Solar Cycles

Chowdhury

Kılçık

Saha

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

Temporal and Periodic Analysis of Penumbra–Umbra Ratio for the Last Four Solar Cycles

Chowdhury,

Kilcik,

Saha

et al. 2024

Sol Phys

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We investigate the long-term dynamic behavior of the sunspot penumbra to umbra area ratio by analyzing the Debrecen Photoheliographic Data (DPD) of sunspot groups during the period 1976–2017 (Solar Cycles 21–24). We consider all types of spots and find that the average penumbra–umbra ratio does not exhibit any significant variation with spot latitudes, solar-cycle phases as well as sunspot-cycle strengths. However, the behavior of this ratio is different when we consider the latitudinal distribution of the northern and southern hemispheres separately. Our analysis indicates that for daily total sunspot area the average spot ratio varies from 5.5 to 6.5 and for very large sunspots (> 5000 $\mu$ μ Hem; one $\mu$ μ Hem is $10^{-6}$ 10 − 6 the area of visual solar hemisphere) its value rises to about 8.3. In the case of the group-sunspot area, the average spot ratio is ∼6.76. Furthermore, we found that this ratio exhibits a trend for both smaller (area <100 $\mu$ μ Hem) and large (area > 100 $\mu$ μ Hem) sunspots. Finally, we report the periodic and quasiperiodic variations present in this ratio time series after applying the multitaper method (MTM) and Morlet-wavelet technique. We found that along with the ∼11-year solar-cycle period, the penumbra to umbra area ratio also shows several midterm variations, specifically, Rieger-type and quasibiennial periodicities. We also found that Rieger-type periods occur in all cycles, but the temporal evolution and the modulation of these types of periodicities are different in different solar cycles.

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