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Related papers: Long-Term Clustering Pattern of Solar Active Regio…

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Apart from the 11-year solar cycle, another periodicity around 155-160 days was discovered during solar cycle 21 in high energy solar flares, and its presence in sunspot areas and strong magnetic flux has been also reported. This…

Solar and Stellar Astrophysics · Physics 2014-11-20 T. V. Zaqarashvili , M. Carbonell , R. Oliver , J. L. Ballster

Studying the hemispheric distribution of active regions (ARs) with different magnetic morphology may clarify the features of the dynamo process that is hidden under the photospheric level. The magnetic flux data for 3047 ARs from the CrAO…

Solar and Stellar Astrophysics · Physics 2024-07-10 A. Zhukova

Long-lasting activity complexes (ACs), characterised as a series of closely located, continuously emerging solar active regions (ARs), are considered generating prominent poleward surges from observations. The surges lead to significant…

Solar and Stellar Astrophysics · Physics 2020-12-02 Zi-Fan Wang , Jie Jiang , Jie Zhang , Jing-Xiu Wang

Solar Cycle 24 data are used to determine how often the Sun emerges sunspots in `activity nests', i.e., regions where sunspots and active regions (ARs) repeatedly emerge. We use the Solar Photospheric Ephemeral Active Region (SPEAR) catalog…

Solar and Stellar Astrophysics · Physics 2026-04-06 Aimee Norton , Alex Mendez , Ruizhu Chen , Mausumi Dikpati , S. Aswin Amirtha Raj

Solar active regions (ARs) are crucial for understanding the long-term evolution of solar activities and predicting eruptive phenomena, including solar flares and coronal mass ejections. However, the cycle-dependent properties in the…

Solar and Stellar Astrophysics · Physics 2025-04-25 Yuxia Liu , Tingting Xu , Miao Wan , Linhua Deng , Xinhua Zhao , Shiyang Qi , Nanbin Xiang , Weihong Zhou

Annual oscillations have been detected in many indices of solar activity during many cycles. Recent multi spacecraft observations of coronal bright points revealed slow retrograde toroidal phase drift (with the speed of 3 m/s of 1 yr…

Long-term records of sunspot number and concentrations of cosmogenic radionuclides (10Be and 14C) on the Earth reveal the variation of the Sun's magnetic activity over hundreds and thousands of years. We identify several clear periods in…

Solar and Stellar Astrophysics · Physics 2015-06-03 T. V. Zaqarashvili , R. Oliver , A. Hanslmeier , M. Carbonell , J. L. Ballester , T. Gachechiladze , I. G. Usoskin

We studied the low-frequency $\lesssim 0.5\;$h$^{-1}$ (long-period $\gtrsim 2\;$h) oscillations of active regions (ARs). The investigation is based on an analysis of a time series built from Solar Dynamics Observatory/Helioseismic and…

Solar and Stellar Astrophysics · Physics 2022-03-22 G. Dumbadze , B. M. Shergelashvili , S. Poedts , T. V. Zaqarashvili , M. Khodachenko , P. De Causmaecker

The study of solar active regions (ARs) is of central importance to a range of fundamental science, as well as the practical applications of space weather. Active region emergence and life cycles are two areas of particular interest, yet…

Solar and Stellar Astrophysics · Physics 2025-10-30 Emily I. Mason , Kara L. Kniezewski

Active regions (ARs) are the main sources of variety in solar dynamic events. Automated detection and identification tools need to be developed for solar features for a deeper understanding of the solar cycle. Of particular interest here…

The solar surface magnetic field is fundamental for modeling the coronal magnetic field, studying the solar dynamo, and predicting solar cycle strength. We perform a continuous simulation of the surface magnetic field from 2010 to 2024,…

Solar and Stellar Astrophysics · Physics 2025-06-03 Ruihui Wang , Jie Jiang , Yukun Luo

Using a recently suggested magneto-morphological classification (MMC, Abramenko, 2021, MNRAS Vol 507) of solar active regions (ARs), we explored 3048 ARs, observed from12 May 1996 to 27 December 2021. Magnetograms were acquired with the…

Solar and Stellar Astrophysics · Physics 2026-01-21 Anastasiya Zhukova , Valentina Abramenko

We developed Long Short-Term Memory (LSTM) models to predict the formation of active regions (ARs) on the solar surface. Using the Doppler shift velocity, the continuum intensity, and the magnetic field observations from the Solar Dynamics…

Solar and Stellar Astrophysics · Physics 2024-09-27 Spiridon Kasapis , Irina N. Kitiashvili , Alexander G. Kosovichev , John T. Stefan

Aims. Solar active regions (ARs), which are formed by flux emergence, serve as the primary sources of solar eruptions. However, the specific physical mechanism that governs the emergence process and its relationship with flare productivity…

Solar and Stellar Astrophysics · Physics 2024-03-28 Zheng Sun , Ting Li , Quan Wang , Shangbin Yang , Mei Zhang , Yajie Chen

In our earlier study of this series (Park et al. 2020, Paper I), we examined the hemispheric sign preference (HSP) of magnetic helicity flux $dH/dt$ across photospheric surfaces of 4802 samples of 1105 unique active regions (ARs) observed…

Solar and Stellar Astrophysics · Physics 2021-04-28 Sung-Hong Park , K. D. Leka , Kanya Kusano

We investigate spatio-temporal evolution of high-degree acoustic mode frequencies of the Sun and the surface magnetic activity, over the course of multiple solar cycles, to improve our understanding of the connection between the solar…

Solar and Stellar Astrophysics · Physics 2023-12-20 Mackenzie A. Baird , Sushanta C. Tripathy , Kiran Jain

Using the data on magnetic field maps and continuum intensity for Solar Cycles 23 and 24, we explored 100 active regions (ARs) that produced M5.0 or stronger flares. We focus on the presence/absence of the emergence of magnetic flux in…

Solar and Stellar Astrophysics · Physics 2024-02-29 Alexander S. Kutsenko , Valentina I. Abramenko , Andrei A. Plotnikov

Recent studies indicate that a small number of rogue solar active regions (ARs) may have a significant impact on the end-of-cycle polar field and the long-term behavior of solar activity. The impact of individual ARs can be qualified based…

Solar and Stellar Astrophysics · Physics 2024-05-13 Ruihui Wang , Jie Jiang , Yukun Luo

Solar active regions (ARs) are the primary drivers of space weather events, making their early prediction crucial for operational forecasting systems. We develop machine learning models capable of predicting the evolution of magnetic flux…

Solar and Stellar Astrophysics · Physics 2026-04-07 Eren Dogan , Spiridon Kasapis , Sarang Patil , Jonas Tirona , John Stefan , Irina Kitiashvili , Mengjia Xu , Alexander Kosovichev

The activity of Sun-like stars is governed by the magnetic field, which is believed to be generated in a thin layer between convective and radiative envelopes. The dynamo layer, also called the tachocline, permits the existence of Rossby…

Solar and Stellar Astrophysics · Physics 2025-10-13 T. V. Zaqarashvili , M. Dikpati , P. A. Gilman
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