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The calling card of solar magnetism is the sunspot cycle, during which sunspots regularly reverse their polarity sense every 11 years. However, a number of more complicated time-dependent behaviors have also been identified. In particular,…

太阳与恒星天体物理 · 物理学 2020-04-06 Loren Matilsky , Juri Toomre

Detailed models of the solar cycle require information about the starting time and rise time as well as the shape and amplitude of the cycle. However, none of these models includes a discussion of the variations in the length of the cycle,…

天体物理学 · 物理学 2007-05-23 Michael L. Rogers , Mercedes T. Richards , Donald St. P. Richards

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…

太阳与恒星天体物理 · 物理学 2025-05-12 Zi-Fan Wang , Jie Jiang , Jing-Xiu Wang

The magnetic fields of solar-type stars are observed to cycle over decadal periods -11 years in the case of the Sun. The fields originate in the turbulent convective layers of stars and have a complex dependency upon stellar rotation rate.…

太阳与恒星天体物理 · 物理学 2017-08-02 A. Strugarek , P. Beaudoin , P. Charbonneau , A. S. Brun , J. -D. do Nascimento

The magnetic cycle on the Sun consists of two consecutive 11-yr sunspot cycles and exhibits a polarity reversal around sunspot maximum. Although solar dynamo theories have progressively become more sophisticated, the details as to how the…

太阳与恒星天体物理 · 物理学 2025-01-29 S. Bellotti , P. Petit , S. V. Jeffers , S. C. Marsden , J. Morin , A. A. Vidotto , C. P. Folsom , V. See , J. -D. do Nascimento

Parameters of magnetic activity on the solar type stars depend on the properties of the dynamo processes operating in stellar convection zones. We apply nonlinear mean-field axisymmetric $\alpha^2\Omega$ dynamo models to calculate of the…

太阳与恒星天体物理 · 物理学 2015-05-08 V. V. Pipin

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…

太阳与恒星天体物理 · 物理学 2015-07-07 K. L. Yeo , N. A. Krivova , S. K. Solanki

The magnetic activity of the Sun becomes stronger and weaker over roughly an 11 year cycle, modulating the radiation and charged particle environment experienced by the Earth as "space weather". Decades of observations from the Mount Wilson…

太阳与恒星天体物理 · 物理学 2017-08-18 Axel Brandenburg , Savita Mathur , Travis S. Metcalfe

The Sun, aside from its eleven year sunspot cycle is additionally subject to long term variation in its activity. In this work we analyse a solar-like convective dynamo simulation, containing approximately 60 magnetic cycles, exhibiting…

太阳与恒星天体物理 · 物理学 2017-10-11 Frederick A. Gent , Maarit J. Käpylä , Jörn Warnecke

We want to study the connections between the magnetic field generated inside the Sun and the solar wind impacting Earth, especially the influence of north-south asymmetry on the magnetic and velocity fields. We study a solar-like 11-year…

太阳与恒星天体物理 · 物理学 2018-09-11 Barbara Perri , Allan Sacha Brun , Victor Réville , Antoine Strugarek

The periods of magnetic activity cycles in the Sun and solar-type stars do not exhibit a simple or even single trend with respect to rotation rate or luminosity. Dynamo models can be used to interpret this diversity, and can ultimately help…

太阳与恒星天体物理 · 物理学 2018-08-15 A. Strugarek , P. Beaudoin , P. Charbonneau , A. S. Brun

Solar magnetic activity shows both smooth secular changes, such as the Grand Modern Maximum, and quite abrupt drops that are denoted as Grand Minima. Direct numerical simulations (DNS) of convection driven dynamos offer one way of examining…

太阳与恒星天体物理 · 物理学 2016-04-13 Maarit J. Käpylä , Petri J. Käpylä , Nigul Olspert , Axel Brandenburg , Jörn Warnecke , Bidya B. Karak , Jaan Pelt

The hemispheric asymmetry of sunspot activity observed possesses a regular component varying on a time scale of several solar cycles whose origin and properties are currently debated. This paper addresses the question of whether the…

太阳与恒星天体物理 · 物理学 2019-05-08 Alexander Nepomnyashchikh , Sudip Mandal , Dipankar Banerjee , Leonid Kitchatinov

The recent paucity of sunspots and the delay in the expected start of Solar Cycle 24 have drawn attention to the challenges involved in predicting solar activity. Traditional models of the solar cycle usually require information about the…

太阳与恒星天体物理 · 物理学 2013-12-05 Mercedes T. Richards , Michael L. Rogers , Donald St. P. Richards

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…

太阳与恒星天体物理 · 物理学 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)…

太阳与恒星天体物理 · 物理学 2015-10-14 Ricky Egeland , Travis S. Metcalfe , Jeffrey C. Hall , Gregory W. Henry

Since a universally accepted dynamo model of grand minima does not exist at the present time, we concentrate on the physical processes which may be behind the grand minima. After summarizing the relevant observational data, we make the…

太阳与恒星天体物理 · 物理学 2015-06-05 Arnab Rai Choudhuri

Magnetic fields generated in the Sun's interior by the solar dynamo mechanism drive solar activity over a range of time-scales. While space-based observations of the Sun's corona exist only for few decades, direct sunspot observations exist…

太阳与恒星天体物理 · 物理学 2023-07-03 Soumyaranjan Dash , Dibyendu Nandy , Ilya Usoskin

The solar cycle onset at mid-latitudes, the slow down of the sunspot drift toward the equator, the tail-like attachment and the overlap of successive cycles at the time of activity minimum are delicate issues in $\alpha\Omega$ dynamo wave…

太阳与恒星天体物理 · 物理学 2016-09-07 R. Simoniello , S. C. Tripathy , K. Jain , F. Hill

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…

太阳与恒星天体物理 · 物理学 2014-07-21 Ilídio Lopes , Dário Passos , Melinda Nagy , Kristof Petrovay