EXPLAINING THE COEXISTENCE OF LARGE-SCALE AND SMALL-SCALE MAGNETIC FIELDS IN FULLY CONVECTIVE STARS
EXPLAINING THE COEXISTENCE OF LARGE-SCALE AND SMALL-SCALE MAGNETIC FIELDS IN FULLY CONVECTIVE STARS
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解释全对流恒星中大尺度和小尺度磁场的共存
DOI：
10.1088/2041-8205/813/2/l31
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Christensen
中科院分区：
文献类型：
--
作者：
Christensen
尽管缺乏一个剪切丰富的速跃层区域，低质量的完全对流（FC）恒星能够产生强磁场，这表明一个发电机机制从根本上不同于太阳发电机在这些对象中工作。本文提出了一个低质量FC星磁场产生的自洽三维模型。该模型利用滞弹性磁流体动力学方程模拟旋转球体中的可压缩对流。一个分布式发电机工作在模型中自发地产生一个偶极占主导地位的表面磁场的观察强度。这个磁场与外层湍流对流的相互作用将其撕碎，产生携带大部分磁通量的小尺度磁场。塞曼多普勒成像技术应用于合成光谱偏振数据的基础上，我们的模型恢复大部分的大规模领域。我们的模型同时再现的形态和大小的大规模的领域，以及小规模的低质量FC恒星上观察到的领域的幅度。
Despite the lack of a shear-rich tachocline region, low-mass fully convective (FC) stars are capable of generating strong magnetic fields, indicating that a dynamo mechanism fundamentally different from the solar dynamo is at work in these objects. We present a self-consistent three-dimensional model of magnetic field generation in low-mass FC stars. The model utilizes the anelastic magnetohydrodynamic equations to simulate compressible convection in a rotating sphere. A distributed dynamo working in the model spontaneously produces a dipole-dominated surface magnetic field of the observed strength. The interaction of this field with the turbulent convection in outer layers shreds it, producing small-scale fields that carry most of the magnetic flux. The Zeeman–Doppler-Imaging technique applied to synthetic spectropolarimetric data based on our model recovers most of the large-scale field. Our model simultaneously reproduces the morphology and magnitude of the large-scale field as well as the magnitude of the small-scale field observed on low-mass FC stars.