DIFFERENTIAL ROTATION IN MAGNETIZED AND NON-MAGNETIZED STARS
DIFFERENTIAL ROTATION IN MAGNETIZED AND NON-MAGNETIZED STARS
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DOI：
10.1088/0004-637x/806/1/10
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发表时间：
2015-04
期刊：
影响因子：
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通讯作者：
Jun Mabuchi;Y. Masada;A. Kageyama
中科院分区：
文献类型：
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作者：
Jun Mabuchi;Y. Masada;A. Kageyama
通过比较磁流体动力学（MHD）模型和相应的流体动力学（HD）模型，研究了磁场对恒星差异自转（DR）的影响.在全球壳几何结构中进行旋转渗透对流的完全可压缩MHD模拟。通过对“Rossby数（Ro）”和“对流Rossby数（Ro conv？> ).”从Ro conv？>依赖正如在早期的研究中观察到的，在HD模型中，旋转轮廓在过渡附近显示出双稳态，而当允许磁场增长时，除了在以反太阳型解为初始条件的模型中，它消失了。我们发现，过渡发生在Ro？1？>在MHD和HD模型中，与滞后无关。考虑到Ro的依赖性，两种模型之间不仅临界值相似，而且转变的尖锐度也相似。发电机产生的磁场和/或滞后对对流运动的影响由Ro反映。这就是为什么考虑到Ro依赖性，过渡是统一的。我们还讨论了磁发电机活动的Ro依赖性，重点是它们与动力学螺旋度剖面的可能关系。
The effects of magnetic field on stellar differential rotation (DR) are studied by comparing magnetohydrodynamic (MHD) models and their hydrodynamic (HD) counterparts in the broad range of rotation rates and across varying initial rotation profiles. Fully compressible MHD simulations of rotating penetrative convection are performed in a full-spherical shell geometry. Critical conditions for the transition of the DR between a faster equator (solar type) and a slower equator (anti-solar type) are explored by focusing on the “Rossby number (Ro)” and the “convective Rossby number ( Ro conv ?> ).” It is confirmed that the transition is more gradual and the critical value for it is higher in the MHD model than in the HD model in view of the Ro conv ?> dependence. As observed in earlier studies, the rotation profile shows a bistability near the transition in the HD model, whereas it disappears when allowing the growth of magnetic fields except in the model taking the anti-solar-type solution as the initial condition. We find that the transition occurs at Ro ≃ 1 ?> both in the MHD and HD models independently of the hysteresis. Not only the critical value but also the sharpness of the transition is similar between the two models in view of the Ro dependence. The influences of the dynamo-generated magnetic field and/or the hysteresis on convective motion are reflected by Ro. This is why the transition is unified in view of the Ro dependence. We also discuss the Ro dependence of magnetic dynamo activities with emphasis on their possible relation to the kinetic helicity profile.