Protoplanetary discs at certain radii exhibit adverse radial entropy gradients that can drive oscillatory convection (`convective overstability'; COS). The ensuing hydrodynamical activity may reshape the radial thermal structure of the disc while mixing solid material radially and vertically or, alternatively, concentrating it in vortical structures. We perform local axisymmetric simulations of the COS using the code SNOOPY, showing first how parasites halt the instability's exponential growth, and second, the different saturation routes it takes subsequently. As the Reynolds and (pseudo-) Richardson numbers increase, the system moves successively from (a) a weakly nonlinear state characterised by relatively ordered nonlinear waves, to (b) wave turbulence, and finally to (c) the formation of intermittent and then persistent zonal flows. In three-dimensions, we expect the latter flows to spawn vortices in the orbital plane. Given the very high Reynolds numbers in protoplanetary discs, the third regime should be the most prevalent. As a consequence, we argue that the COS is an important dynamical process in planet formation, especially near features such as dead zone edges, ice lines, gaps, and dust rings.
Planet-Disk Interactions and the Convective Overstability. I. Low Mass Planets
Iowa State University（爱荷华州立大学）；Institute of Astronomy and Astrophysics, Academia Sinica（中央研究院天文及天文物理研究所）；National Center for Theoretical Sciences（国家理论科学中心）
Thermal baroclinic instabilities in accretion disks I: Combined dispersion relation for Goldreich-Schubert-Fricke Instability and Convective Overstability in disks around young stars
本文研究了年轻恒星周围盘中的热斜压不稳定性，推导了 GSF 和 COS 的组合色散关系并确定了新稳定性判据，发现斜压盘大气始终存在浮力不稳定方向，且长冷却时间下 GSF 模式会伴随相似增长率的 COS 模式。
Thermal instabilities in accretion disks II: Numerical Experiments for the Goldreich-Schubert-Fricke Instability and the Convective Overstability in disks around young stars
本文通过数值实验验证了吸积盘中 GSF 与 COS 两种热不稳定性的理论增长率，发现 GSF 增长更快但近中平面停止，COS 最终主导，并揭示了观测所需分辨率要求。
MRI-active inner regions of protoplanetary discs. I. A detailed model of disc structure
短周期的超级地球大小的行星很常见。要解释它们是如何在目前的轨道附近形成的，需要了解原行星盘内部区域的结构。以前的研究认为，热的内部原行星盘是不稳定的磁旋转不稳定性（MRI）由于钾的热电离，并在这个MRI活动区的外缘形成的局部气体压力最大值。在这里，我们提出了一个稳态模型的内盘粘性增生，主要是由于MRI。在我们的模型中，内部盘的结构和MRI粘度是完全耦合的，此外，我们考虑了许多过程中省略了以前这样的模型，包括盘加热吸积和恒星辐射，垂直能量输送，现实的尘埃不透明度，尘埃盘电离和非热源电离的影响。对于一个标准气体吸积率（$\dot{M}$ $\sim$ $10^{-8}$ M $_\odot$ yr $^{-1}$）和小尘埃颗粒的太阳质量的恒星周围的光盘，我们发现，光盘的内部是光学厚，吸积热主要是在中面附近释放。因此，无论是光盘中平面的温度和压力最大值的位置，只有轻微的恒星辐射的影响，和内部光盘也对流不稳定。如前所述，内盘主要是通过尘埃颗粒的电子和钾离子发射电离的，这些离子在高温下抵消了颗粒上自由电荷的吸附。我们的研究结果表明，压力最大值的位置是由阈值温度以上的电子和离子发射变得有效。
Radiation Hydrodynamics of Self-gravitating Protoplanetary Disks II. Accretion, Migration, Spin, and Internal Structure of GI Fragments
Institute for Advanced Study, Tsinghua University（清华大学高等研究院）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；Department of Astronomy, Tsinghua University（清华大学天文系）
The refractory fraction of phosphorus in planet-forming discs
Institute for Theoretical and Computation Physics, Graz University of Technology（格拉茨工业大学理论与计算物理研究所）；Tartu Observatory, University of Tartu（塔尔图大学塔尔图天文台）；Department of Physics and Astronomy, University College London（伦敦大学学院物理与天文学系）；Space Research Institute, Austrian Academy of Sciences（奥地利科学院空间研究所）
