二维径向分层天体物理圆盘中模式的线性耦合

等温剪切盒中尘埃驱动的垂直剪切不稳定性：I. 无尘埃反馈的湍流与气体动力学

Dust-driven vertical shear instability in an isothermal shearing box: I. Turbulence and gas dynamics without dust feedback

研究等温剪切盒中无尘埃反馈的尘埃驱动垂直剪切不稳定性（DVSI），采用FARGO3D模拟，发现其可驱动各向异性湍流与垂直混合，或在分层流不稳定性中起重要作用。

Giant planet formation in radially structured protoplanetary discs

Our recent N-body simulations of planetary system formation, incorporating models for the main physical processes thought to be important during the building of planets (i.e. gas disc evolution, migration, planetesimal/boulder accretion, gas accretion onto cores, etc.), have been successful in reproducing some of the broad features of the observed exoplanet population (e.g. compact systems of low mass planets, hot Jupiters), but fail completely to form any surviving cold Jupiters. The primary reason for this failure is rapid inward migration of growing protoplanets during the gas accretion pha…

局部等温径向结构自引力盘中的单臂螺旋

One-armed spirals in locally isothermal, radially structured self-gravitating discs

我们描述了一种新的机制，导致不稳定的非轴对称波在天体物理光盘施加径向温度梯度。例如，这可能适用于原行星盘的外部。我们使用线性密度波理论表明，非轴对称扰动一般不保存其角动量在强迫温度梯度的存在下。这意味着线性扰动和背景盘之间的角动量交换。特别是，当扰动是一个低频的拖尾波和磁盘温度向外下降，这种相互作用是不稳定的，并导致波的增长。我们证明了这种现象，通过局部等温盘在2D中使用FARGO代码和在3D中与ZEUS-MP和PLUTO代码的数值流体动力学模拟。我们考虑径向结构的光盘与自引力区域保持稳定的温度梯度的情况下。然而，当施加温度梯度时，我们观察到单臂螺旋模式（方位波数$m=1$）的指数增长，其中在旋臂的大部分之外具有共旋半径，从而导致接近静止的单臂螺旋图案。这种单臂螺旋的发展并不需要中心恒星的运动，正如以前的研究所发现的那样。由于强迫温度梯度的不稳定并不明确需要光盘自重，我们认为这种机制也可能会影响低频单臂振荡非自引力光盘。

Radially resolved simulations of collapsing pebble clouds in protoplanetary discs

We study the collapse of pebble clouds with a statistical model to find the internal structure of comet-sized planetesimals. Pebble-pebble collisions occur during the collapse and the outcome of these collisions affect the resulting structure of the planetesimal. We expand our previous models by allowing the individual pebble sub-clouds to contract at different rates and by including the effect of gas drag on the contraction speed and in energy dissipation. Our results yield comets that are porous pebble-piles with particle sizes varying with depth. In the surface layers there is a mixture of …

Spiral arms in thermally stratified protoplanetary discs

Spiral arms have been observed in nearly a dozen protoplanetary discs in near-infrared scattered light and recently also in the sub-millimetre continuum. While one of the most compelling explanations is that they are driven by planetary or stellar companions, in all but one cases such companions have not yet been detected and there is even ambiguity on whether the planet should be located inside or outside the spirals. Here we use 3D hydrodynamic simulations to study the morphology of spiral density waves launched by embedded planets taking into account the vertical temperature gradient, a nat…

Local gravitational instability of stratified rotating fluids: 3D criteria for gaseous discs

Fragmentation of rotating gaseous systems via gravitational instability is believed to be a crucial mechanism in several astrophysical processes, such as formation of planets in protostellar discs, of molecular clouds in galactic discs, and of stars in molecular clouds. Gravitational instability is fairly well understood for infinitesimally thin discs. However, the thin-disc approximation is not justified in many cases, and it is of general interest to study the gravitational instability of rotating fluids with different degrees of rotation support and stratification. We derive dispersion rela…

The convective stability of fully stratified baroclinic discs

We examine the convective stability of hydrodynamic discs with full stratification in the local approximation and in the presence of thermal diffusion (or relaxation). Various branches of the relevant axisymmetric dispersion relation derived by Urpin (2003) are discussed. We find that when the vertical Richardson number is larger than or equal to the radial one (i.e. $|Ri_z|\geq|Ri_x|$) and wavenumbers are comparable (i.e. $|k_x|\sim|k_z|$) the disc becomes unstable, even in the presence of radial and vertical stratifications with $Ri_x>0$ and $Ri_z>0$. The origin of this resides in an hybrid …

在径向结构原行星盘中通过卵石吸积形成行星的N体模拟

$N$-body simulation of planetary formation through pebble accretion in a radially structured protoplanetary disk

本文通过N体模拟研究径向结构原行星盘中卵石吸积对行星形成的影响，发现不连续边界处原行星可在约10^4年内增长至地球质量，并普遍发生巨型碰撞，最终可能形成类似太阳系的行星系统。