论文标题
外部全球磁盘的湍流：MRI还是VSI？
Turbulence in outer protoplanetary disks: MRI or VSI?
论文作者
论文摘要
外部球门磁盘（PPD）可以受到磁化不稳定性（MRI）和垂直剪切不稳定性（VSI）的约束。尽管这两个过程均可驱动磁盘中的湍流，但现有的数值模拟已经分别研究了它们。在本文中，我们对具有双极扩散和瞬时冷却的外部PPD进行了全局3D非理想的磁性水力动力学（MHD）模拟，从而使两种不稳定性进行了导电。鉴于探索了AmbipolareElsässer数字（$ AM $）的范围，因此发现，当Ambipolar扩散强劲时，VSI湍流在MRI上占主导地位（$ AM = 0.1 $）； VSI和MRI可以以$ AM = 1 $共存；当双极扩散较弱时，MRI淹没了VSI（$ am = 10 $）。角动量传输过程主要是由MHD风驱动的，而在大多数情况下，由于MRI和/或VSI湍流引起的粘性积聚会产生适度的贡献。在强烈的双极扩散式磁盘（$ AM \ leq1 $）中，自发的磁通量浓度和环形下结构的形成在存在VSI的情况下保持强大。双极扩散是导致磁通量浓度现象而不是对流的主要原因。
The outer protoplanetary disks (PPDs) can be subject to the magnetorotational instability (MRI) and the vertical shear instability (VSI). While both processes can drive turbulence in the disk, existing numerical simulations have studied them separately. In this paper, we conduct global 3D non-ideal magnetohydrodynamic (MHD) simulations for outer PPDs with ambipolar diffusion and instantaneous cooling, and hence conductive to both instabilities. Given the range of ambipolar Elsässer numbers ($Am$) explored, it is found that the VSI turbulence dominates over the MRI when ambipolar diffusion is strong ($Am=0.1$); the VSI and MRI can co-exist for $Am=1$; and the VSI is overwhelmed by the MRI when ambipolar diffusion is weak ($Am=10$). Angular momentum transport process is primarily driven by MHD winds, while viscous accretion due to MRI and/or VSI turbulence makes a moderate contribution in most cases. Spontaneous magnetic flux concentration and formation of annular substructures remain robust in strong ambipolar diffusion dominated disks ($Am\leq1$) with the presence of the VSI. Ambipolar diffusion is the major contributor to the magnetic flux concentration phenomenon rather than advection.
