揭示旋转主序星长期流体动力学过程的诊断
Diagnoses to unravel secular hydrodynamical processes in rotating main sequence stars
摘要：
本文详细分析了旋转恒星辐射区角动量和化学物质输运的主要物理过程。我们专注于的情况下，纬向环流和剪切引起的湍流只包括在模拟中。我们的分析是基于一个2-D表示的长期流体动力学，这是治疗使用球谐函数展开。我们提出了一个完整的重建与诊断的角动量，热量和化学物质的运输的温度和平均分子量的波动和相关的dronal循环。在本文件中，这些工具被用来验证分析的两个主要序列恒星模型的1.5和20 Msun的流体动力学已被广泛研究的文献。我们得到一个清晰的可视化和精确的估计不同的条款进入角动量和热输运方程在辐射区。这使我们能够证实在过去的十年中获得的主要成果Zahn，Maeder，和合作者有关的长期流体动力学等对象。我们着重于角动量损失和结构调整驱动的纬向环流。通过详细的计算和分离的各种成分，我们首次定量地证实了这个环流的熵平流是非常好的平衡的正压效应和热弛豫在大多数的主要序列的演变。这使我们能够得到简化的热弛豫在这个阶段。赤道气流反过来平流热量，并产生温度波动，通过热成风引起差异旋转，从而关闭运输回路。
英文摘要：
(Abridged) We present a detailed analysis of the main physical processes responsible for the transport of angular momentum and chemical species in the radiative regions of rotating stars. We focus on cases where meridional circulation and shear-induced turbulence only are included in the simulations. Our analysis is based on a 2-D representation of the secular hydrodynamics, which is treated using expansions in spherical harmonics. We present a full reconstruction of the meridional circulation and of the associated fluctuations of temperature and mean molecular weight along with diagnosis for the transport of angular momentum, heat and chemicals. In the present paper these tools are used to validate the analysis of two main sequence stellar models of 1.5 and 20 Msun for which the hydrodynamics has been previously extensively studied in the literature. We obtain a clear visualization and a precise estimation of the different terms entering the angular momentum and heat transport equations in radiative zones. This enables us to corroborate the main results obtained over the past decade by Zahn, Maeder, and collaborators concerning the secular hydrodynamics of such objects. We focus on the meridional circulation driven by angular momentum losses and structural readjustements. We confirm quantitatively for the first time through detailed computations and separation of the various components that the advection of entropy by this circulation is very well balanced by the barotropic effects and the thermal relaxation during most of the main sequence evolution. This enables us to derive simplifications for the thermal relaxation on this phase. The meridional currents in turn advect heat and generate temperature fluctuations that induce differential rotation through thermal wind thus closing the transport loop.
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