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Small-scale dynamo action is often held responsible for the generation of quiet-Sun magnetic fields. We aim to determine the excitation conditions and saturation level of small-scale dynamos in non-rotating turbulent convection at low…

Solar and Stellar Astrophysics · Physics 2018-06-06 Petri J. Käpylä , Maarit J. Käpylä , Axel Brandenburg

A number of observational and theoretical aspects of solar magnetoconvection are considered in this review. We discuss recent developments in our understanding of the small-scale structure of the magnetic field on the solar surface and its…

Solar and Stellar Astrophysics · Physics 2015-12-29 J. M. Borrero , S. Jafarzadeh , M. Schüssler , S. K. Solanki

Regions of quiet Sun generally exhibit a complex distribution of small-scale magnetic field structures, which interact with the near-surface turbulent convective motions. Furthermore, it is probable that some of these magnetic fields are…

Solar and Stellar Astrophysics · Physics 2015-06-18 Paul J. Bushby , Benjamin Favier

We demonstrate that a magneto-convection simulation incorporating essential physical processes governing solar surface convection exhibits turbulent small-scale dynamo action. By presenting a derivation of the energy balance equation and…

Solar and Stellar Astrophysics · Physics 2010-04-23 Jonathan Pietarila Graham , Robert Cameron , Manfred Schuessler

Magnetic fields are usually observed in the quiet Sun as small-scale elements that cover the entire solar surface (the `salt and pepper' patterns in line-of-sight magnetograms). By using 3D radiative MHD numerical simulations we find that…

Solar and Stellar Astrophysics · Physics 2015-08-19 I. N. Kitiashvili , A. G. Kosovichev , N. N. Mansour , A. A. Wray

Various aspects of the magnetism of the quiet sun are reviewed. The suggestion that a small scale dynamo acting at granular scales generates what we call the quiet sun fields is studied in some detail. Although dynamo action has been proved…

Solar and Stellar Astrophysics · Physics 2015-06-12 V. Martinez Pillet

Despite the lack of a shear-rich tachocline region low-mass fully convective stars are capable of generating strong magnetic fields, indicating that a dynamo mechanism fundamentally different from the solar dynamo is at work in these…

Solar and Stellar Astrophysics · Physics 2015-11-11 Rakesh K. Yadav , Ulrich R. Christensen , Julien Morin , Thomas Gastine , Ansgar Reiners , Katja Poppenhaeger , Scott J. Wolk

Natural dynamos such as planets and stars generate global scale magnetic field despite the inferred presence of small scale turbulence. Such systems are known as large scale dynamos and are typically driven by convection and influenced by…

Fluid Dynamics · Physics 2022-02-24 Ming Yan , Michael A. Calkins

The small-scale magnetic field is ubiquitous at the solar surface---even at high latitudes. From observations we know that this field is uncorrelated (or perhaps even weakly anticorrelated) with the global sunspot cycle. Our aim is to…

Solar and Stellar Astrophysics · Physics 2016-01-11 Bidya Binay Karak , Axel Brandenburg

A physically consistent model of magnetic field generation by convection in a rotating spherical shell with a minimum of parameters is applied to the Sun. Despite its unrealistic features the model exhibits a number of properties resembling…

Solar and Stellar Astrophysics · Physics 2015-06-04 R. D. Simitev , F. H. Busse

As we resolve ever smaller structures in the solar atmosphere, it has become clear that magnetism is an important component of those small structures. Small-scale magnetism holds the key to many poorly understood facets of solar magnetism…

Astrophysics · Physics 2008-12-25 A. G. de Wijn , J. O. Stenflo , S. K. Solanki , S. Tsuneta

We live near a magnetic star whose cycles of activity are driven by dynamo action beneath the surface. In the solar convection zone, rotation couples with plasma motions to build highly organized magnetic fields that erupt at the surface…

Solar and Stellar Astrophysics · Physics 2015-05-20 Benjamin P Brown

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

Small-scale turbulent dynamo is responsible for the amplification of magnetic fields on scales smaller than the driving scale of turbulence in diverse astrophysical media. Most earlier dynamo theories concern the kinematic regime and…

Astrophysics of Galaxies · Physics 2021-06-25 Siyao Xu , Alex Lazarian

All cool main sequence stars including our Sun are thought to have magnetic fields. Observations of the Sun revealed that even in quiet regions small-scale turbulent magnetic fields are present. Simulations further showed that such magnetic…

Solar and Stellar Astrophysics · Physics 2023-02-01 V. Witzke , H. B. Duehnen , A. I. Shapiro , D. Przybylski , T. S. Bhatia , R. Cameron , S. K. Solanki

Magnetic fields on small scales are ubiquitous in the universe. Though they can often be observed in detail, their generation mechanisms are not fully understood. One possibility is the so-called small-scale dynamo (SSD). Prevailing…

Solar and Stellar Astrophysics · Physics 2023-06-08 Jörn Warnecke , Maarit J. Korpi-Lagg , Frederick A. Gent , Matthias Rheinhardt

An update is given on the current status of solar and stellar dynamos. At present, it is still unclear why stellar cycle frequencies increase with rotation frequency in such a way that their ratio increases with stellar activity. The…

Solar and Stellar Astrophysics · Physics 2015-06-15 Axel Brandenburg

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

Context: Convectively-driven flows play a crucial role in the dynamo processes that are responsible for producing magnetic activity in stars and planets. It is still not fully understood why many astrophysical magnetic fields have a…

Solar and Stellar Astrophysics · Physics 2018-05-09 P. J. Bushby , P. J. Käpylä , Y. Masada , A. Brandenburg , B. Favier , C. Guervilly , M. J. Käpylä

We study the amplification of magnetic fields during the formation of primordial halos. The turbulence generated by gravitational infall motions during the formation of the first stars and galaxies can amplify magnetic fields very…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Jennifer Schober , Dominik Schleicher , Christoph Federrath , Simon Glover , Ralf Klessen , Robi Banerjee
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