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Core convection and dynamo activity deep within rotating A-type stars of 2 solar masses are studied with 3--D nonlinear simulations. Our modeling considers the inner 30% by radius of such stars, thus capturing within a spherical domain the…

Astrophysics · Physics 2008-11-26 Allan Sacha Brun , Matthew K. Browning , Juri Toomre

Early-type stars have convective cores due to a steep temperature gradient produced by the CNO cycle. These cores can host dynamos, and the generated magnetic fields can be relevant to explain the magnetism observed in Ap/Bp stars. Our main…

Solar and Stellar Astrophysics · Physics 2024-11-27 J. P. Hidalgo , P. J. Käpylä , D. R. G Schleicher , C. A. Ortiz-Rodríguez , F. H. Navarrete

We present the results of 3--D simulations of core convection within A-type stars of 2 solar masses, at a range of rotation rates. We consider the inner 30% by radius of such stars, thereby encompassing the convective core and some of the…

Astrophysics · Physics 2008-11-26 Matthew Browning , Allan Sacha Brun , Juri Toomre

Stars of sufficiently low mass are convective throughout their interiors, and so do not possess an internal boundary layer akin to the solar tachocline. Because that interface figures so prominently in many theories of the solar magnetic…

Solar and Stellar Astrophysics · Physics 2015-05-20 Matthew Browning

We present three-dimensional nonlinear magnetohydrodynamic simulations of the interiors of fully convective M-dwarfs. Our models consider 0.3 solar-mass stars using the Anelastic Spherical Harmonic code, with the spherical computational…

Astrophysics · Physics 2009-11-13 Matthew Browning

The advent of massively parallel supercomputing has begun to permit explicit 3--D simulations of turbulent convection occurring within the cores of early-type main sequence stars. Such studies should complement the stellar structure and…

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

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

Increasing evidence is becoming available about not only the surface differential rotation of rapidly rotating cool stars but, in a small number of cases, also about temporal variations, which possibly are analogous to the solar torsional…

Astrophysics · Physics 2009-11-10 E. Covas , D. Moss , R. Tavakol

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

Main-sequence massive stars possess convective cores that likely harbor strong dynamo action. To assess the role of core convection in building magnetic fields within these stars, we employ the 3-D anelastic spherical harmonic (ASH) code to…

Solar and Stellar Astrophysics · Physics 2015-05-20 Kyle C. Augustson , Allan S. Brun , Juri Toomre

The objective of this paper is to investigate whether a convective dynamo can account quantitatively for the observed lower limit of X-ray surface flux in solar-type main sequence stars. Our approach is to use 3D numerical simulations of a…

Astrophysics · Physics 2009-11-11 D. J. Bercik , G. H. FIsher , C. M. Johns-Krull , W. P. Abbett

Recent observations indicate that fully convective stars can effectively build magnetic fields without the aid of a tachocline of shear, that those fields can possess large-scale components, and that they may sense the effects of rotation.…

Astrophysics · Physics 2009-11-13 Matthew Browning , Gibor Basri

According to our understanding of stellar evolution, early-type stars have radiative envelopes and convective cores due to a steep temperature gradient produced by the CNO cycle. Some of these stars (mainly, the subclasses Ap and Bp) have…

Solar and Stellar Astrophysics · Physics 2023-03-21 J. P. Hidalgo , P. J. Käpylä , C. A. Ortiz-Rodríguez , F. H. Navarrete , B. Toro , D. R. G. Schleicher

The global-scale dynamo action achieved in a simulation of a Sun-like star rotating at thrice the solar rate is assessed. The 3-D MHD Anelastic Spherical Harmonic (ASH) code, augmented with a viscosity minimization scheme, is employed to…

Solar and Stellar Astrophysics · Physics 2015-03-17 Kyle Augustson , Sacha Brun , Mark 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

Numerical MHD simulations play increasingly important role for understanding mechanisms of stellar magnetism. We present simulations of convection and dynamos in density-stratified rotating spherical fluid shells. We employ a new 3D…

Solar and Stellar Astrophysics · Physics 2015-09-03 Radostin D. Simitev , Alexander G. Kosovichev , Friedrich H. Busse

We review the current state of knowledge of magnetic fields inside stars, concentrating on recent developments concerning magnetic fields in stably stratified (zones of) stars, leaving out convective dynamo theories and observations of…

Solar and Stellar Astrophysics · Physics 2017-04-11 J. Braithwaite , H. C. Spruit

Young solar-type stars rotate rapidly and many are magnetically active; some undergo magnetic cycles similar to the 22-year solar activity cycle. We conduct simulations of dynamo action in rapidly rotating suns with the 3D MHD anelastic…

Solar and Stellar Astrophysics · Physics 2011-03-28 Benjamin P. Brown , Mark S. Miesch , Matthew K. Browning , Allen Sacha Brun , Juri Toomre

Large-scale magnetic fields of Ap/Bp stars are stable over long timescales and have typically simple dipolar geometries, leading to the idea of a fossil origin. These stars are also expected to have convective cores that can host strong…

Solar and Stellar Astrophysics · Physics 2025-07-16 J. P. Hidalgo , P. J. Käpylä , D. R. G Schleicher , C. A. Ortiz-Rodríguez , F. H. Navarrete

Magnetic fields play a role in almost all stages of stellar evolution. Most low-mass stars, including the Sun, show surface fields that are generated by dynamo processes in their convective envelopes. Intermediate-mass stars do not have…

Solar and Stellar Astrophysics · Physics 2016-01-26 D. Stello , M. Cantiello , J. Fuller , D. Huber , R. A. Garcia , T. R. Bedding , L. Bildsten , V. Silva Aguirre
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