It is well-known that the cores of massive stars sustain a stellar dynamo with a complex magnetic field configuration. However, the same cannot be said for the field's strength and geometry at the convective–radiative boundary, which are crucial when performing asteroseismic inference. In this Letter, we present 3D magnetohydrodynamic (MHD) simulations of a 7 M⊙ mid-main-sequence star, with particular attention given to the convective–radiative boundary in the near-core region. Our simulations reveal that the toroidal magnetic field is significantly stronger than the poloidal field in this region, contrary to recent assumptions. Moreover, the rotational shear layer, also important for asteroseismic inference, is specifically confined within the extent of the Brunt–Väisälä frequency peak. These results, which are based on the inferred properties of HD 43317, have widespread implications for asteroseismic studies of rotation, mixing, and magnetism in stars. While we expect our results to be broadly applicable across stars with similar Brunt–Väisälä frequency profiles and stellar masses, we also expect the MHD parameters (e.g., Rem) and the initial stellar rotation rate to impact the geometry of the field and differential rotation at the convective–radiative interface.

中文翻译：

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关于大质量恒星中近核磁场的几何学


众所周知，大质量恒星的核心维持着具有复杂磁场配置的恒星发电机。然而，对流-辐射边界处的场强度和几何形状却并非如此，这在执行星震推理时至关重要。在这封信中，我们介绍了一颗 7 M⊙ 中主序星的 3D 磁流体动力学 （MHD） 模拟，特别关注了近核心区域的对流-辐射边界。我们的模拟表明，与最近的假设相反，该区域的环形磁场明显强于极地磁场。此外，旋转剪切层对于星震推理也很重要，它特别局限在 Brunt-Väisälä 频率峰值的范围内。这些结果基于 HD 43317 的推断特性，对恒星旋转、混合和磁的星震研究具有广泛的意义。虽然我们预计我们的结果将广泛适用于具有相似 Brunt-Väisälä 频率分布和恒星质量的恒星，但我们也预计 MHD 参数（例如 Rem）和初始恒星旋转速率会影响对流-辐射界面处的场几何和差分旋转。