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Related papers: Long-term Study of the Sun and Its Implications to…

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The Sun's magnetic field shows the 11-year solar cycle and shorter periodicities, popularly known as the quasi-biennial oscillations (QBOs) and Rieger-type periods, or ``season of the Sun." Although several theories have been proposed to…

Solar and Stellar Astrophysics · Physics 2025-10-28 Pawan Kumar , Belur Ravindra , Partha Chowdhury , Bidya Binay Karak

A deep learning model is often considered a black-box model, as its internal workings tend to be opaque to the user. Because of the lack of transparency, it is challenging to understand the reasoning behind the model's predictions. Here, we…

Machine Learning · Computer Science 2025-08-25 Adam O. Rawashdeh , Jason T. L. Wang , Katherine G. Herbert

We report our first results on comparing the variations of the solar internal rotation with solar activity, as predicted by non-linear solar dynamo modelling, with helioseismic measurements using the SOHO MDI data.

Astrophysics · Physics 2007-05-23 S. Vorontsov , R. Tavakol , E. Covas , D. Moss

The Sun is a magnetic star whose magnetism and cyclic activity is linked to the existence of an internal dynamo. We aim to understand the establishment of the solar magnetic 22-yr cycle, its associated butterfly diagram and field parity…

Astrophysics · Physics 2008-11-26 L. Jouve , A. S. Brun

Rotation is a prominent feature of the Sun, and it plays a crucial role in the generation and dynamic evolution of solar magnetic fields. The daily composite time series of Ca II K plage areas from 1907 February 1 to 2023 December 31 is…

Solar and Stellar Astrophysics · Physics 2025-12-18 N. B. Xiang , X. H. Zhao , L. H. Deng , F. Y. Li , M. Wan , S. Y. Qi

Inter-cycle variations in the series of 11-year solar activity cycles have a significant impact on both the space environment and climate. Whether solar cycle variability is dominated by deterministic chaos or stochastic perturbations…

Solar and Stellar Astrophysics · Physics 2025-05-12 Zi-Fan Wang , Jie Jiang , Jing-Xiu Wang

The large-scale magnetic field in the Sun varies with a period of approximately 22 years, although the amplitude of the cycle is subject to long-term modulation with recurrent phases of significantly reduced magnetic activity. It is…

Solar and Stellar Astrophysics · Physics 2015-06-19 Laura Cole , Paul Bushby

Solar activity is studied using a cluster analysis of the time-fluctuations of the sunspot number. It is shown that in an Historic period the high activity components of the solar cycles exhibit strong clustering, whereas in a Modern period…

Astrophysics · Physics 2010-11-02 A. Bershadskii

In the era of space exploration, the implications of space weather have become increasingly evident. Central to this is the phenomenon of coronal holes, which can significantly influence the functioning of satellites and aircraft. These…

Solar and Stellar Astrophysics · Physics 2024-06-24 Juyoung Yun

The correlation between solar irradiance and the 11-year solar activity cycle is evident in the body of measurements made from space, which extend over the past four decades. Models relating variation in solar irradiance to photospheric…

Solar and Stellar Astrophysics · Physics 2015-07-07 K. L. Yeo , N. A. Krivova , S. K. Solanki

Solar magnetic activity is expressed via variations of sunspots and active regions varying on different timescales. The most accepted is an 11-year period supposedly induced by the electromagnetic solar dynamo mechanism. There are also some…

Solar and Stellar Astrophysics · Physics 2023-01-19 Valentina V. Zharkova , Irina Vasilieva , Simon Shepherd , Elena Popova

A growing body of evidence suggests that multiple dynamo mechanisms can drive magnetic variability on different timescales, not only in the Sun but also in other stars. Many solar activity proxies exhibit a quasi-biennial ($\sim$2 year)…

Solar and Stellar Astrophysics · Physics 2015-10-14 Ricky Egeland , Travis S. Metcalfe , Jeffrey C. Hall , Gregory W. Henry

It is well accepted that the solar cycle originates from a magnetohydrodynamics dynamo deep inside the Sun. Many dynamo models have long been proposed based on a lot of observational constraints. In this paper, using 342 NSO/Kitt Peak solar…

Astrophysics · Physics 2009-06-23 W. B. Song

Recent data on superflares on sun-like stars and radiocarbon data on solar activity in the past are both indicative of transient epochs of unusually high magnetic activity. We propose an explanation for the grand activity maxima in the…

Solar and Stellar Astrophysics · Physics 2016-05-05 L. L. Kitchatinov , S. V. Olemskoy

Observations of sun-like stars rotating faster than our current sun tend to exhibit increased magnetic activity as well as magnetic cycles spanning multiple years. Using global simulations in spherical shells to study the coupling of…

Solar and Stellar Astrophysics · Physics 2015-05-20 Nicholas J. Nelson , Benjamin P. Brown , Matthew K. Browning , Allan Sacha Brun , Mark S. Miesch , Juri Toomre

The sunspot number data during the past 400 years indicates that both the profile and the amplitude of the solar cycle have large variations. Some precursors of the solar cycle were identified aiming to predict the solar cycle. The polar…

Solar and Stellar Astrophysics · Physics 2015-06-15 Jie Jiang

The 11-yr cycle of sunspots undergo amplitude modulation over longer timescales. As a part of this long-term modulation in solar activity, the decennial rhythm occasionally breaks, with quiescent phases with very few sunspots observed over…

Solar and Stellar Astrophysics · Physics 2025-09-05 Chitradeep Saha , Sanghita Chandra , Dibyendu Nandy

A two-wave dynamo model was recently proposed by Zharkova et al. (2015, Zh15 henceforth), which aims at long-term predictions of solar activity for millennia ahead and backwards. Here we confront the backward model predictions for the last…

Solar and Stellar Astrophysics · Physics 2015-12-18 I. Usoskin , G. Kovaltsov

The strength and morphology of the Sun's magnetic field evolves significantly during the solar cycle, with the overall polarity of the Sun's magnetic field reversing during the maximum of solar activity. Long-term changes are also observed…

Solar and Stellar Astrophysics · Physics 2023-11-01 Adam J. Finley , Allan Sacha Brun

Prediction of the Sun's magnetic activity is important because of its effect on space environment and climate. However, recent efforts to predict the amplitude of the solar cycle have resulted in diverging forecasts with no consensus.…

Solar and Stellar Astrophysics · Physics 2012-12-07 Bidya Binay Karak , Dibyendu Nandy