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The Sun's variability is controlled by the progression and interaction of the magnetized systems that form the 22-year magnetic activity cycle (the "Hale Cycle'') as they march from their origin at $\sim$55 degrees latitude to the equator,…

Solar and Stellar Astrophysics · Physics 2021-12-07 Robert Leamon , Scott McIntosh , Alan Title

We argue that the most prominent temporal features of the solar dynamo, in particular the Hale cycle, the Suess-de Vries cycle (associated with variations of the Gnevyshev-Ohl rule), Gleissberg-type cycles, and grand minima can be…

Solar and Stellar Astrophysics · Physics 2021-06-23 Frank Stefani , Rodion Stepanov , Tom Weier

Magnetic activity cycles are an important phenomenon in both the Sun and other stars. The shape of the solar cycle is commonly characterised by a fast rise and a slower decline, but not much attention has been paid to the shape of cycles in…

Solar and Stellar Astrophysics · Physics 2020-07-01 T. Willamo , T. Hackman , J. J. Lehtinen , M. J. Käpylä , N. Olspert , M. Viviani , J. Warnecke

The bulk of available stellar activity observations is frequently checked for the manifestation of signs in comparison with the known characteristic of solar magnetic modulation. The problem is that stellar activity records are usually an…

Solar and Stellar Astrophysics · Physics 2020-06-03 R. Stepanov , N. I. Bondar' , M. M. Katsova , D. Sokoloff , P. Frick

Solar irradiance measurements are limited to the last few decades, requiring reconstructions to assess solar variability on longer timescales and its impact on Earth's climate. We present the first physics-based reconstruction of total…

Solar and Stellar Astrophysics · Physics 2026-05-22 D. Temaj , N. A. Krivova , S. K. Solanki , I. G. Usoskin , T. Chatzistergos

A variety of indices have been proposed in order to represent the many different observables modulated by the solar cycle. Most of these indices are highly correlated with each other owing to their intrinsic link with the solar magnetism…

Solar and Stellar Astrophysics · Physics 2017-05-22 Ilaria Ermolli , Kiyoto Shibasaki , Andrey Tlatov , Lidia van Driel-Gesztelyi

A large variation in 14 C around AD 775 has been considered to be caused by one or more solar super-flares within one year. We critically review all known aurora reports from Europe as well as the Near, Middle, and Far East from AD 731 to…

Solar and Stellar Astrophysics · Physics 2015-05-27 Ralph Neuhaeuser , Dagmar L. Neuhaeuser

Maunder Minimum forms an archetype for the Grand minima, and detailed knowledge of its temporal development has important consequences for the solar dynamo theory dealing with long-term solar activity evolution. Here we reconsider the…

Solar and Stellar Astrophysics · Physics 2015-05-27 J. M. Vaquero , M. C. Gallego , I. G. Usoskin , G. A. Kovaltsov

The data of sunspot numbers, sunspot areas and solar flare index during cycle 23 are analyzed to investigate the intermediate-term periodicities. Power spectral analysis has been performed separately for the data of the whole disk, northern…

Solar and Stellar Astrophysics · Physics 2009-11-16 Bhuwan Joshi , P. Pant , P. K. Manoharan

The solar cycle is a complex phenomenon. To comprehensively understand it, we have to study various tracers. The most important component of this complex is the solar dynamo, which is understood as self-excitation of the solar magnetic…

Solar and Stellar Astrophysics · Physics 2025-01-10 V. N. Obridko , A. S. Shibalova , D. D. Sokoloff

The magnetic activity of the Sun, as manifested in the sunspot cycle, originates deep within its convection zone through a dynamo mechanism which involves non-trivial interactions between the plasma and magnetic field in the solar interior.…

Solar and Stellar Astrophysics · Physics 2015-05-13 Dibyendu Nandy

The Sun's activity cycle governs the radiation, particle and magnetic flux in the heliosphere creating hazardous space weather. Decadal-scale variations define space climate and force the Earth's atmosphere. However, predicting the solar…

Solar and Stellar Astrophysics · Physics 2019-09-11 Prantika Bhowmik , Dibyendu Nandy

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

Stellar magnetic fields are produced by a magnetohydrodynamic dynamo mechanism working in their interior -- which relies on the interaction between plasma flows and magnetic fields. The Sun, being a well-observed star, offers an unique…

Solar and Stellar Astrophysics · Physics 2015-06-03 Dibyendu Nandy

The solar magnetic activity consists of two periodic components: the main cycle with a period of 11 yr and a shorter cycle with a period of ~2 yrs. The origin of this second periodicity is still not well understood. We use almost 15 yrs of…

Solar and Stellar Astrophysics · Physics 2015-06-11 R. Simoniello , K. Jain , S. C. Tripathy , S. Turck-Chieze , W. Finsterle , M. Roth

In 1965 Paul D. Jose published his discovery that both the motion of the Sun about the center of mass of the solar system and periods comprised of eight Hale magnetic sunspot cycles with a mean period of ~22.37 years have a matching…

Solar and Stellar Astrophysics · Physics 2017-01-19 Gerald E. Pease , Gregory S. Glenn

Solar activity undergoes a variation over time scales of several months known as Rieger-type periodicity, which usually occurs near maxima of sunspot cycles. An early analysis showed that the periodicity appears only in some cycles, and is…

We discuss one important aspect of Waldmeier effect which says that the stronger cycles rise rapidly than weaker cycles. We studied four different data set of solar activity indices, and find strong linear correlation between rise rates and…

Solar and Stellar Astrophysics · Physics 2011-02-22 Bidya Binay Karak , Arnab Rai Choudhuri

The Sun exhibits a well-observed modulation in the number of spots on its disk over a period of about 11 years. From the dawn of modern observational astronomy sunspots have presented a challenge to understanding -- their quasi-periodic…

Solar and Stellar Astrophysics · Physics 2020-12-09 Scott W. McIntosh , Sandra C. Chapman , Robert J. Leamon , Ricky Egeland , Nicholas W. Watkins

Herein we adopt a multi-scale dynamical spectral analysis technique to compare and study the dynamical evolution of the harmonic components of the overlapping ACRIMSAT/ACRIM3, SOHO/VIRGO and SORCE/TIM total solar irradiance (TSI) records…

General Physics · Physics 2013-11-28 Nicola Scafetta , Richard C. Willson