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The solar magnetic activity cycle is responsible for periodic episodes of severe space weather, which can perturb satellite orbits, interfere with communications systems, and bring down power grids. Much progress has recently been made in…

Astrophysics · Physics 2007-05-23 T. S. Metcalfe , T. J. Henry , M. Knolker , D. R. Soderblom

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…

Solar and Stellar Astrophysics · Physics 2017-08-18 Axel Brandenburg , Savita Mathur , Travis S. Metcalfe

Dynamical systems with complex delayed interactions arise commonly when propagation times are significant, yielding complicated oscillatory instabilities. In this Letter, we introduce a class of systems with multiple, hierarchically long…

Pattern Formation and Solitons · Physics 2015-06-19 Serhiy Yanchuk , Giovanni Giacomelli

The model that describes operation of dynamo in fully convective stars is presented. It is based on representation of stellar magnetic field as a superposition of finite number of poloidal and toroidal free damping modes. In the frame of…

Astrophysics · Physics 2009-11-13 D. D. Sokoloff , S. N. Nefedov , A. A. Ermash , S. A. Lamzin

The mean-field dynamo model is employed to study the non-linear dynamo regimes in a fully convective star of mass 0.3$M_{\odot}$ rotating with period of 10 days. For the intermediate value of the parameter of the turbulent magnetic Prandl…

Solar and Stellar Astrophysics · Physics 2017-02-01 V. V. Pipin

The interstellar medium of the Milky Way and nearby disk galaxies harbours large-scale coherent magnetic fields of Microgauss strength, that can be explained via the action of a mean-field dynamo. As in our previous work, we aim to quantify…

Astrophysics of Galaxies · Physics 2020-03-18 Oliver Gressel , Detlef Elstner

We study the time variations of the cycles of 20 active stars based on decades-long photometric or spectroscopic observations. A method of time-frequency analysis, as discussed in a companion paper, is applied to the data. Fifteen stars…

Solar and Stellar Astrophysics · Physics 2015-05-13 K. Oláh , Z. Kolláth , T. Granzer , K. G. Strassmeier , A. F. Lanza , S. Järvinen , H. Korhonen , S. L. Baliunas , W. Soon , S. Messina , G. Cutispoto

During the first 40 s after their birth, proto-neutron stars are expected to be subject to at least two types of instability: the convective instability and the neutron-finger one. Both instabilities involve convective motions and hence can…

Astrophysics · Physics 2009-06-23 L. Naso , L. Rezzolla , A. Bonanno , L. Paternò

Local shearing box simulations of stratified magneto rotational turbulence invariably exhibit cyclic field patterns which propagate away from the disc midplane. A common explanation for this is magnetic buoyancy. The recent analysis by Shi…

Earth and Planetary Astrophysics · Physics 2015-05-18 Oliver Gressel

Fluctuations in the Sun's magnetic activity, including episodes of grand minima such as the Maunder minimum have important consequences for space and planetary environments. However, the underlying dynamics of such extreme fluctuations…

Solar and Stellar Astrophysics · Physics 2014-06-12 Soumitra Hazra , Dário Passos , Dibyendu Nandy

In this paper, we present a semi-empirical model of isolated binary star formation. This model includes the effects of turbulence in the initial state of the gas, and has binary orbital parameters consistent with observation. Our…

Astrophysics · Physics 2009-11-07 Robert T. Fisher

The well known mean-field model of a turbulence driven dynamo is reviewed in relation to Laboratory experiments in which a turbulent cascade is created by a pair of large rotors. It is argued that in such experiments the alpha-effect,…

Fluid Dynamics · Physics 2012-10-16 J B Taylor

"The purpose of numerical models is not numbers but insight." (Hamming) In the spirit of this adage, and of Don Cox's approach to scientific speaking, we discuss the questions that the latest generation of numerical models of the…

Astrophysics · Physics 2015-06-24 Mordecai-Mark Mac Low , Miguel A. de Avillez , Maarit J. Korpi

Using a thin flux tube model in a rotating spherical shell of turbulent, solar-like convective flows, we find that the distribution of emerging flux tubes in our simulation is inhomogeneous in longitude, with properties similar to those of…

Solar and Stellar Astrophysics · Physics 2015-06-15 Maria A. Weber , Yuhong Fan , Mark S. Miesch

Semiconductor $p^+ - p^- - n - p^+ - n^{++}$ structures with large junction and contact areas are treated as 1 \times 2-dimensional active media, in which self-organized pattern formation can be expected. The local bistable behavior of the…

patt-sol · Physics 2009-10-31 A. V. Gorbatyuk , F. -J. Niedernostheide

Multistationarity in biological systems is a mechanism of cellular decision making. In particular, signaling pathways regulated by protein phosphorylation display features that facilitate a variety of responses to different biological…

Subcellular Processes · Quantitative Biology 2011-07-05 Elisenda Feliu , Carsten Wiuf

We discover multipole-mode solitons supported by the surface between two distinct periodic lattices imprinted in Kerr-type nonlinear media. Such solitons are possible because the refractive index modulation at both sides of the interface…

Optics · Physics 2009-11-11 Yaroslav V. Kartashov , Lluis Torner

We consider a parametrically driven damped discrete nonlinear Schr\"odinger (PDDNLS) equation. Analytical and numerical calculations are performed to determine the existence and stability of fundamental discrete bright solitons. We show…

Pattern Formation and Solitons · Physics 2012-06-13 M. Syafwan , H. Susanto , S. M. Cox

Mean-field dynamo theory has important applications in solar physics and galactic magnetism. We discuss some of the many turbulence effects relevant to the generation of large-scale magnetic fields in the solar convection zone. The…

Solar and Stellar Astrophysics · Physics 2023-11-23 Axel Brandenburg , Detlef Elstner , Youhei Masada , Valery Pipin

Active agents with time-delayed interactions arise naturally in various real-world systems, such as biological systems, transportation networks and robotic swarms. Such systems are typically modeled as Delay Differential Equations (DDEs)…

Dynamical Systems · Mathematics 2025-09-03 Yu Wang , Andreas Amann , Jinde Cao , Jürgen Kurths , Serhiy Yanchuk