标题： 旋转恒星辐射区中的垂直剪切不稳定性：全科里奥利加速度和热扩散的影响 显示英文标题

标题： Vertical shear instabilities in rotating stellar radiation zones: effects of the full Coriolis acceleration and thermal diffusion

摘要： 旋转对恒星的结构和演化有着深远的影响。 为了构建一致的一维或多维恒星结构和演化模型，我们必须系统地评估由径向和纬向差旋转引起的流体动力学不稳定性所导致的动量和物质湍流输运。 在这项工作中，我们研究了这些区域中的垂直剪切不稳定性。 考虑一般纬度下的完整旋转矢量时，包含了完整的科里奥利加速度。 我们通过考虑具有双曲正切分布的典型剪切流来制定问题。 使用数值和渐近Wentzel-Kramers-Brillouin-Jeffreys (WKBJ)方法，对该基础流进行了线性稳定性分析。 识别并探讨了两种类型的不稳定性：剪切流存在拐点时发生的拐点不稳定性，以及由于离心加速度与压力梯度之间不平衡而产生的惯性不稳定性。 这两种不稳定性随着热扩散变强或分层变弱而被促进。 根据广泛范围的余纬度和旋转-剪切比及旋转-分层比的参数调查发现，完整的科里奥利加速度效应更为复杂。 此外，还推导了新的垂直涡粘度公式，以模拟由每种不稳定性引发的湍流输运。 我们预见，在缓慢旋转恒星的强烈分层辐射区的赤道区域，拐点不稳定性将负责湍流输运，而在快速旋转恒星的弱分层辐射区的极地区域，惯性不稳定性将触发湍流。 显示英文摘要

摘要： Rotation deeply impacts the structure and the evolution of stars. To build coherent 1D or multi-D stellar structure and evolution models, we must systematically evaluate the turbulent transport of momentum and matter induced by hydrodynamical instabilities of radial and latitudinal differential rotation in stably stratified thermally diffusive stellar radiation zones. In this work, we investigate vertical shear instabilities in these regions. The full Coriolis acceleration with the complete rotation vector at a general latitude is taken into account. We formulate the problem by considering a canonical shear flow with a hyperbolic-tangent profile. We perform linear stability analysis on this base flow using both numerical and asymptotic Wentzel-Kramers-Brillouin-Jeffreys (WKBJ) methods. Two types of instabilities are identified and explored: inflectional instability, which occurs in the presence of an inflection point in shear flow, and inertial instability due to an imbalance between the centrifugal acceleration and pressure gradient. Both instabilities are promoted as thermal diffusion becomes stronger or stratification becomes weaker. Effects of the full Coriolis acceleration are found to be more complex according to parametric investigations in wide ranges of colatitudes and rotation-to-shear and rotation-to-stratification ratios. Also, new prescriptions for the vertical eddy viscosity are derived to model the turbulent transport triggered by each instability. We foresee that the inflectional instability will be responsible for turbulent transport in the equatorial region of strongly-stratified radiative zones in slowly rotating stars while the inertial instability triggers turbulence in the polar regions of weakly-stratified radiative zones in fast-rotating stars.