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One of the puzzling features of solar magnetism is formation of long-living compact magnetic structures; such as sunspots and pores, in the highly turbulent upper layer of the solar convective zone. We use realistic radiative 3D MHD…

Solar and Stellar Astrophysics · Physics 2015-05-18 I. N. Kitiashvili , A. G. Kosovichev , A. A. Wray , N. N. Mansour

The Sun's magnetic dynamo cycle features a distinct pattern: a propagating region of sunspot emergence appears around 30 degrees latitude and vanishes near the equator every 11 years. Moreover, longitudinal flows called "torsional…

Our Sun exhibits strong convective dynamo action which results in magnetic flux bundles emerging through the stellar surface as magnetic spots. Global-scale dynamo action is believed to generate large-scale magnetic structures in the deep…

Solar and Stellar Astrophysics · Physics 2014-03-05 Nicholas J. Nelson , Mark S. Miesch

The presence of magnetic field is crucial in the transport of energy through the solar atmosphere. Recent ground-based and space-borne observations of the quiet Sun have revealed that magnetic field accumulates at photospheric heights, via…

Solar and Stellar Astrophysics · Physics 2019-06-19 Juan Martínez-Sykora , Viggo H. Hansteen , Boris Gudiksen , Mats Carlsson , Bart De Pontieu , Milan Gosic

We investigate small-scale dynamo action in the solar convection zone through a series of high resolution MHD simulations in a local Cartesian domain with 1$R_\odot$ (solar radius) of horizontal extent and a radial extent from 0.715 to…

Solar and Stellar Astrophysics · Physics 2015-06-23 H. Hotta , M. Rempel , T. Yokoyama

The current dynamo paradigm for the Sun and sun-like stars places the generation site for strong toroidal magnetic structures deep in the solar interior. Sunspots and star-spots on sun-like stars are believed to arise when sections of these…

Solar and Stellar Astrophysics · Physics 2015-05-30 Nicholas J. Nelson , Benjamin P. Brown , Allan Sacha Brun , Mark S. Miesch , Juri Toomre

Observations of sun-like stars rotating faster than our current sun tend to exhibit increased magnetic activity as well as magnetic cycles spanning multiple years. Using global simulations in spherical shells to study the coupling of…

Solar and Stellar Astrophysics · Physics 2015-05-20 Nicholas J. Nelson , Benjamin P. Brown , Matthew K. Browning , Allan Sacha Brun , Mark S. Miesch , Juri Toomre

Although the magnetic fields in the quiet Sun account for the majority of the magnetic energy in the solar photosphere, inferring their exact spatial distribution, origin, and evolution poses an important challenge because the signals lie…

Solar and Stellar Astrophysics · Physics 2024-10-03 Elias Ebert , Ivan Milic , Juan Manuel Borrero

Stellar dynamos are driven by complex couplings between rotation and turbulent convection, which drive global-scale flows and build and rebuild stellar magnetic fields. When stars like our sun are young, they rotate much more rapidly than…

In addition to sunspots, which represent the most easily visualized manifestation of solar magnetism, cutting-edge observations of the solar atmosphere have uncovered a plethora of magnetic flux tubes, down to the resolving power of modern…

Solar and Stellar Astrophysics · Physics 2025-02-27 M. Stangalini , G. Verth , V. Fedun , D. Perrone , M. Berretti , P. Bushby , S. Jafarzadeh , D. B. Jess , F. Giannattasio , P. H. Keys , R. Bruno , F. Berrilli

We explore the nature of the small-scale solar dynamo by tracking magnetic features. We investigate two previously-explored categories of the small-scale solar dynamo: shallow and deep. Recent modeling work on the shallow dynamo has…

Solar and Stellar Astrophysics · Physics 2015-06-19 Derek A. Lamb , Timothy A. Howard , Craig E. DeForest

We report the results of a magneto-hydrodynamic (MHD) simulation of a convective dynamo in a model solar convective envelope driven by the solar radiative diffusive heat flux. The convective dynamo produces a large-scale mean magnetic field…

Solar and Stellar Astrophysics · Physics 2014-06-18 Yuhong Fan , Fang Fang

We present a radiative magnetohydrodynamics simulation of the formation of an Active Region on the solar surface. The simulation models the rise of a buoyant magnetic flux bundle from a depth of 7.5 Mm in the convection zone up into the…

Solar and Stellar Astrophysics · Physics 2015-05-19 M. C. M. Cheung , M. Rempel , A. M. Title , M. Schüssler

Surface observations indicate that the speed of the solar meridional circulation in the photosphere varies in anti-phase with the solar cycle. The current explanation for the source of this variation is that inflows into active regions…

Solar and Stellar Astrophysics · Physics 2017-11-29 D. Passos , M. Miesch , G. Guerrero , P. Charbonneau

For Sun-like stars, the generation of toroidal magnetic field from poloidal magnetic field is an essential piece of the dynamo mechanism powering their magnetism. Previous authors have estimated the net toroidal flux generated in each…

Solar and Stellar Astrophysics · Physics 2024-01-23 Adam J. Finley , Sacha A. Brun , Antoine Strugarek , Robert Cameron

We analyze recent high resolution photospheric small-scale dynamo simulations that were computed with the MURaM radiative MHD code. We focus the analysis on newly forming downflow lanes in exploding granules since they show how weakly…

Solar and Stellar Astrophysics · Physics 2018-06-27 Matthias Rempel

The study of spatial and temporal scales on which small magnetic structures (magnetic elements) are organized in the quiet Sun may be approached by determining how they are transported on the solar photosphere by convective motions. The…

Solar and Stellar Astrophysics · Physics 2015-06-16 F. Giannattasio , D. Del Moro , F. Berrilli , L. Bellot Rubio , M. Gosic , D. Orozco Suarez

When our Sun was young it rotated much more rapidly than now. Observations of young, rapidly rotating stars indicate that many possess substantial magnetic activity and strong axisymmetric magnetic fields. We conduct simulations of dynamo…

Solar and Stellar Astrophysics · Physics 2010-11-15 Benjamin P. Brown , Matthew K. Browning , Allen Sacha Brun , Mark S. Miesch , Juri Toomre

The convective envelopes of cool main-sequence stars harbour magnetic fields with a complex global and local structure. These fields affect the near-surface convection and the outer stellar atmospheres in many ways and are responsible for…

Solar and Stellar Astrophysics · Physics 2015-09-02 Benjamin Beeck , Manfred Schüssler , Robert H. Cameron , Ansgar Reiners

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