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We study the dynamical and statistical properties of turbulent cross-helicity (correlation of the aligned fluctuating velocity and magnetic field components). We derive an equation governing generation and evolution of the turbulent…

Solar and Stellar Astrophysics · Physics 2015-05-28 V. V. Pipin , K. M. Kuzanyan , H. Zhang , A. G. Kosovichev

It is often claimed that there is not only one, but two different types of solar dynamos: the one that is responsible for the appearance of sunspots and the 11-yr cycle, frequently referred to as the "global dynamo", and a statistically…

Solar and Stellar Astrophysics · Physics 2015-06-12 J. O. Stenflo

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

While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local…

Generation and diffusion of the magnetic field on the Sun is a key mechanism responsible for solar activity on all spatial and temporal scales - from the solar cycle down to the evolution of small-scale magnetic elements in the quiet Sun.…

Solar and Stellar Astrophysics · Physics 2011-12-14 V. I. Abramenko , V. B. Yurchyshyn , P. R. Goode

This article reviews some of the leading results obtained in solar dynamo physics by using temporal oscillator models as a tool to interpret observational data and dynamo model predictions. We discuss how solar observational data such as…

Solar and Stellar Astrophysics · Physics 2014-07-21 Ilídio Lopes , Dário Passos , Melinda Nagy , Kristof Petrovay

Prediction of solar activity cycles is challenging because physical processes inside the Sun involve a broad range of multiscale dynamics that no model can reproduce and because the available observations are highly limited and cover mostly…

Solar and Stellar Astrophysics · Physics 2020-09-30 Irina N. Kitiashvili

We study turbulent generation of large-scale magnetic fields using nonlinear dynamo models for solar-type stars in the range of rotational periods from 14 to 30 days. Our models take into account non-linear effects of dynamical quenching of…

Solar and Stellar Astrophysics · Physics 2016-06-08 Valery Pipin , Alexander Kosovichev

For the first time we reconstruct the magnetic helicity density of global axisymmetric field of the Sun using method proposed by Brandenburg et al. (2003) and Pipin et al. (2013). To determine the components of the vector potential, we…

Solar and Stellar Astrophysics · Physics 2015-06-18 V. V. Pipin , A. A. Pevtsov

The evolution of the solar activity comprises, apart from the well-known 11-year cycle, various temporal scales ranging from months up to the secondary cycles known as mid-term oscillations. Its nature deserves a physical explanation. In…

Solar and Stellar Astrophysics · Physics 2020-08-04 D. D. Sokoloff , A. S. Shibalova , V. N. Obridko , V. V. Pipin

One of the most striking manifestations of orderly behavior emerging out of complex interactions in any astrophysical system is the 11-year cycle of sunspots. However, direct sunspot observations and reconstructions of long-term solar…

Solar and Stellar Astrophysics · Physics 2025-04-24 Chitradeep Saha , Suprabha Mukhopadhyay , Dibyendu Nandy

Sunspots are of basic interest in the study of the Sun. Their relevance ranges from them being an activity indicator of magnetic fields to being the place where coronal mass ejections and flares erupt. They are therefore also an important…

Solar and Stellar Astrophysics · Physics 2018-05-24 Illa R. Losada , Jörn Warnecke , Kolja Glogowski , Markus Roth , Axel Brandenburg , Nathan Kleeorin , Igor Rogachevskii

A striking feature of the solar cycle is that at the beginning, sunspots appear around mid-latitudes, and over time the latitudes of emergences migrate towards the equator. The maximum level of activity varies from cycle to cycle. For…

Solar and Stellar Astrophysics · Physics 2024-12-25 Akash Biswas

We explore the impact of magnetic helicity conservation on the mean-field solar dynamo using the axisymmetric dynamo model which includes the subsurface shear. Our results support the recent findings by Hubbard & Brandenburg (2012), who…

Solar and Stellar Astrophysics · Physics 2015-06-12 V. V. Pipin , D. D. Sokoloff , H. Zhang , K. M. Kuzanyan

Computational heliophysics has shed light on the fundamental physical processes inside the Sun, such as the differential rotation, meridional circulation, and dynamo-generation of magnetic fields. However, despite the substantial advances,…

Solar and Stellar Astrophysics · Physics 2023-01-25 A. G. Kosovichev , G. Guerrero , A. M. Stejko , V. V. Pipin , A. V. Getling

In 1844 Schwabe discovered that the number of sunspots increased and decreased over a period of about 11 years, that variation became known as the sunspot cycle. Almost eighty years later, Hale described the nature of the Sun's magnetic…

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

After summarizing the relevant observational data, we discuss how a study of flux tube dynamics in the solar convection zone helps us to understand the formation of sunspots. Then we introduce the flux transport dynamo model and assess its…

Solar and Stellar Astrophysics · Physics 2015-06-05 Arnab Rai Choudhuri

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

Although sunspots have been systematically observed on the Sun's surface over the last four centuries, their magnetic properties have been revealed and documented only since the early 1900s. Sunspots typically appear in pairs of opposite…

Solar and Stellar Astrophysics · Physics 2019-09-25 Soumitra Hazra , Dibyendu Nandy