BUOYANT MAGNETIC LOOPS IN A GLOBAL DYNAMO SIMULATION OF A YOUNG SUN
BUOYANT MAGNETIC LOOPS IN A GLOBAL DYNAMO SIMULATION OF A YOUNG SUN
复制标题
年轻太阳的全球发电机模拟中的浮力磁环
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
J. Toomre
中科院分区：
文献类型：
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作者：
N. Nelson;B. Brown;A. Brun;M. Miesch;J. Toomre
目前太阳和类太阳恒星的发电机模式为太阳内部深处强烈的环状磁结构提供了生成场所。太阳黑子和类太阳恒星上的恒星黑子被认为是当这些磁结构的部分变得非常不稳定并从内部深处上升到光球层时产生的。在这里，我们提出了第一个三维全球磁流体(MHD)模拟，其中湍流对流、分层和旋转结合在一起，产生一个发电机，自一致地产生浮力磁环。我们模拟了具有太阳层结的球壳中的恒星对流和发电机作用，但自转速度比目前的太阳速率快三倍。强环向磁场是通过对流区的发电机作用实现的。通过转向亚格子尺度湍流的动态Smagorinsky模型，我们在模拟中获得了相当大的扩散减少。这使得这些环中的最强磁场区域通过磁浮力不稳定性和对流巨型单体的平流的组合而上升到对流区的顶部。这种产生浮环的全球模拟代表着在结合发电机作用和磁通涌现的数值模型方面向前迈出的重要一步。
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 starspots on Sun-like stars are believed to arise when sections of these magnetic structures become buoyantly unstable and rise from the deep interior to the photosphere. Here, we present the first three-dimensional global magnetohydrodynamic (MHD) simulation in which turbulent convection, stratification, and rotation combine to yield a dynamo that self-consistently generates buoyant magnetic loops. We simulate stellar convection and dynamo action in a spherical shell with solar stratification, but rotating three times faster than the current solar rate. Strong wreaths of toroidal magnetic field are realized by dynamo action in the convection zone. By turning to a dynamic Smagorinsky model for subgrid-scale turbulence, we here attain considerably reduced diffusion in our simulation. This permits the regions of strongest magnetic field in these wreaths to rise toward the top of the convection zone via a combination of magnetic buoyancy instabilities and advection by convective giant cells. Such a global simulation yielding buoyant loops represents a significant step forward in combining numerical models of dynamo action and flux emergence.
影响因子：
1.3
作者：
N. A. Berkoff;E. Kersalé-;S. Tobias
通讯作者：
N. A. Berkoff;E. Kersalé-;S. Tobias