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Stars and planets in close systems are magnetised but the influence of magnetic fields on their tidal responses (and vice versa) and dissipation rates has not been well explored. We present exploratory nonlinear magnetohydrodynamical (MHD)…

Solar and Stellar Astrophysics · Physics 2025-07-18 Aurélie Astoul , Adrian J. Barker

Magnetohydrodynamic star-in-a-box simulations of convection and dynamos in a solar-like star with different rotation rates are presented. These simulations produce solar-like differential rotation with a fast equator and slow poles, and…

Solar and Stellar Astrophysics · Physics 2022-06-08 Petri J. Käpylä

Evidence of surface magnetism is now observed on an increasing number of cool stars. The detailed manner by which dynamo-generated magnetic fields giving rise to starspots traverse the convection zone still remains unclear. Some insight…

Solar and Stellar Astrophysics · Physics 2017-09-20 Maria A. Weber , Matthew K. Browning , Suzannah Boardman , Joshua Clarke , Samuel Pugsley , Edward Townsend

Many stars across all classes possess strong enough magnetic fields to influence dynamical flow of material off the stellar surface. For the case of massive stars (O and B types), about 10\% of them harbour strong, globally ordered (mostly…

Solar and Stellar Astrophysics · Physics 2023-04-05 Asif ud-Doula , Stan Owocki

Stably stratified fluid layers are common in gaseous planets, stellar interiors, and planetary cores, and have long been considered incapable of sustaining dynamo action. Here, we show that semiconvection - driven by a destabilizing thermal…

Earth and Planetary Astrophysics · Physics 2025-11-26 Paul Pružina , David Cébron , Nathanaël Schaeffer

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

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

Several solar-like stars exhibit cyclic magnetic activity similar to the Sun as found in photospheric and chromospheric emission. We want to understand the physical mechanism involved in rotational dependence of these activity cycle…

Solar and Stellar Astrophysics · Physics 2018-08-22 Jörn Warnecke

Compression of the stellar winds from rapidly rotating hot stars is described by the wind compression model. However, it was also shown that rapid rotation leads to rotational distortion of the stellar surface, resulting in the appearance…

Solar and Stellar Astrophysics · Physics 2014-10-22 Zuzana Cariková , Augustin Skopal

Stellar activity is fundamental to stellar evolution and the formation and habitability of exoplanets. The interaction between convective motions and rotation in cool stars results in a dynamo process that drives magnetic surface activity.…

Modeling the surface brightness distribution of stars is of prime importance to interpret observations. Nevertheless, this remains quite challenging for cool stars as it requires one to model the MHD turbulence that develops in their…

Solar and Stellar Astrophysics · Physics 2024-03-14 C. Pinçon , L. Petitdemange , R. Raynaud , L. J. Garcia , A. Guseva , M. Rieutord , E. Alecian

Recently, surface magnetic field maps had been acquired for a small sample of active M dwarfs, showing that fully convective stars (spectral types ~M4 and later) host intense (~kG), mainly axi-symmetrical poloidal fields. In particular, the…

Solar and Stellar Astrophysics · Physics 2015-03-17 A. A. Vidotto , M. Jardine , M. Opher , J. -F. Donati , T. I. Gombosi

Global and semi-global convective dynamo simulations of solar-like stars are known to show a transition from an anti-solar (fast poles, slow equator) to solar-like (fast equator, slow poles) differential rotation (DR) for increasing…

Solar and Stellar Astrophysics · Physics 2019-11-25 M. Viviani , M. J. Käpylä , J. Warnecke , P. J. Käpylä , M. Rheinhardt

M dwarf's atmosphere is expected to be highly magnetized. The magnetic energy can be responsible for heating the stellar chromosphere and corona, and driving the stellar wind. The nonlinear propagation of Alfv\'en wave is the promising…

Solar and Stellar Astrophysics · Physics 2021-09-29 Takahito Sakaue , Kazunari Shibata

The presence of a strong magnetic field is a feature common to a significant fraction of degenerate stars, yet little is understood about field origin and evolution. New observational constraints from volume-limited surveys point to a more…

Solar and Stellar Astrophysics · Physics 2022-08-24 Stefano Bagnulo , John D. Landstreet

During their main sequence evolution, massive stars can develop convective regions very close to their surface. These regions are caused by an opacity peak associated with iron ionization. Cantiello et al. (2009) found a possible connection…

Solar and Stellar Astrophysics · Physics 2011-08-26 Matteo Cantiello , Jonathan Braithwaite , Axel Brandenburg , Fabio Del Sordo , Petri Käpylä , Norbert Langer

The dynamo action achieved in the convective cores of main-sequence massive stars is explored here through 3D global simulations of convective core dynamos operating within a young $\Msun{10}$ B-type star, using the anelastic spherical…

Solar and Stellar Astrophysics · Physics 2016-10-05 Kyle C. Augustson , Allan Sacha Brun , Juri Toomre

Long-term ideal and resistive magnetohydrodynamics (MHD) simulations in full general relativity are performed for a massive neutron star formed as a remnant of binary neutron star mergers. Neutrino radiation transport effects are taken into…

High Energy Astrophysical Phenomena · Physics 2021-03-17 Masaru Shibata , Sho Fujibayashi , Yuichiro Sekiguchi

We carry out three-dimensional MHD simulations of star formation in turbulent, magnetized clouds, including ambipolar diffusion and feedback from protostellar outflows. The calculations focus on relatively diffuse clouds threaded by a…

Astrophysics · Physics 2009-11-13 Fumitaka Nakamura , Zhi-Yun Li

Rotation and magnetism are increasingly recognized as important phenomena in stellar evolution. Surface magnetic fields from a few to $20{,}000\,$G have been observed and models have suggested that magnetohydrodynamic transport of angular…

Solar and Stellar Astrophysics · Physics 2018-04-04 Leo G. Quentin , Christopher A. Tout