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We performed kinematic studies of the evolution of small-scale magnetic fields in the surface laters of M-dwarfs. We solved the induction equation for a prescribed velocity field, magnetic Reynolds number, and boundary conditions in a…

Astrophysics · Physics 2009-11-07 S. B. F. Dorch , H. -G. Ludwig

Recently, we have developed a method useful for mapping large-scale horizontal velocity fields in the solar photosphere. The method was developed, tuned and calibrated using the synthetic data. Now, we applied the method to the series of…

Astrophysics · Physics 2009-11-13 Michal Svanda , Mirek Klvana , Michal Sobotka , Vaclav Bumba

We present a realistic numerical model of sunspot and active region formation based on the emergence of flux bundles generated in a solar convective dynamo. To this end we use the magnetic and velocity fields in a horizontal layer near the…

Solar and Stellar Astrophysics · Physics 2017-09-20 Feng Chen , Matthias Rempel , Yuhong Fan

A model for the solar dynamo, consistent in global flow and numerical method employed with the differential rotation model, is developed. The magnetic turbulent diffusivity is expressed in terms of the entropy gradient, which is controlled…

Solar and Stellar Astrophysics · Physics 2017-06-28 L. L. Kitchatinov , A. A. Nepomnyashchikh

In this Letter we present a seismological detection of a rising motion of magnetic flux in the shallow convection zone of the Sun, and show estimates of the emerging speed and its decelerating nature. In order to evaluate the speed of…

Solar and Stellar Astrophysics · Physics 2015-06-15 Shin Toriumi , Stathis Ilonidis , Takashi Sekii , Takaaki Yokoyama

(abidged) Context: Stellar convection zones are characterized by vigorous high-Reynolds number turbulence at low Prandtl numbers. Aims: We study the dynamo and differential rotation regimes at varying levels of viscous, thermal, and…

Solar and Stellar Astrophysics · Physics 2017-02-22 P. J. Käpylä , M. J. Käpylä , N. Olspert , J. Warnecke , A. Brandenburg

We present numerical simulations of three-dimensional compressible magnetoconvection in a rotating rectangular box that represents a section of the solar convection zone. The box contains a convectively unstable layer, surrounded by stably…

Astrophysics · Physics 2009-11-07 M. Ossendrijver , M. Stix , A. Brandenburg

The onset of dynamo action is investigated within the context of a newly developed low Rossby, low magnetic Prandtl number, convection-driven dynamo model. This multiscale model represents an asymptotically exact form of an $\alpha^2$ mean…

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

We simulate the buoyant rise of a magnetic flux rope from the solar convection zone into the corona to better understand the energetic coupling of the solar interior to the corona. The magnetohydrodynamic model addresses the physics of…

Solar and Stellar Astrophysics · Physics 2015-06-03 Fang Fang , Ward Manchester , William P. Abbett , Bart van der Holst

We discuss recent advances made in modelling the complex magnetohydrodynamics of the Sun using our anelastic spherical harmonics (ASH) code. We have conducted extensive 3--D simulations of compressible convection in rotating spherical…

Astrophysics · Physics 2007-05-23 Allan Sacha Brun , Juri Toomre

We study how active-region-scale flux tubes rise buoyantly from the base of the convection zone to near the solar surface by embedding a thin flux tube model in a rotating spherical shell of solar-like turbulent convection. These toroidal…

Solar and Stellar Astrophysics · Physics 2015-06-11 Maria A. Weber , Yuhong Fan , Mark S. Miesch

Some of the quiet solar magnetic flux could be attributed to a small-scale dynamo (SSD) operating in the convection zone. An SSD operating in cool main-sequence stars is expected to affect the atmospheric structure, in particular the…

Solar and Stellar Astrophysics · Physics 2024-12-24 Tanayveer S. Bhatia , Robert H. Cameron , Hardi Peter , Sami K. Solanki

Recent analyses of helioseismological observations seem to suggest the presence of two new phenomena connected with the dynamics of the solar convective zone. Firstly, there are present torsional oscillations with periods of about 11 years,…

Astrophysics · Physics 2009-10-31 Eurico Covas , Reza Tavakol , David Moss

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

We carry out high-resolution calculations for the stellar convection zone. The main purpose of this study is to investigate the effect of a small-scale dynamo on the differential rotation. The solar differential rotation deviates from the…

Solar and Stellar Astrophysics · Physics 2018-07-04 H. Hotta

We investigate how the strength of the Lorentz force alters stellar convection zone dynamics in a suite of buoyancy-dominated, three-dimensional, spherical shell convective dynamo models. This is done by varying only the magnetic Prandtl…

Solar and Stellar Astrophysics · Physics 2025-08-28 Krista M. Soderlund , Paula Wulff , Petri Käpylä , Jonathan M. Aurnou

This paper considers the dominant dynamical, thermal and rotational balances within the solar convection zone. The reasoning is such that: Coriolis forces balance pressure gradients. Background vortex stretching, baroclinic torques and…

Solar and Stellar Astrophysics · Physics 2020-10-30 Geoffrey M. Vasil , Keith Julien , Nicholas A. Featherstone

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

We derive horizontal fluid motions on the solar surface over large areas covering the quiet-Sun magnetic network from local correlation tracking of convective granules imaged in continuum intensity and Doppler velocity by the Helioseismic…

Solar and Stellar Astrophysics · Physics 2016-06-29 C. R. Sangeetha , S. P. Rajaguru