Sub-stellar objects exhibit photometric variability, which is believed to be caused by a number of processes, such as magnetically-driven spots or inhomogeneous cloud coverage. Recent models have shown that turbulent flows and waves, including internal gravity waves, may play an important role in cloud evolution.
The aim of this paper is to investigate the effect of IGW on dust nucleation and dust growth, and whether observations of the resulting cloud structures could be used to recover atmospheric density information.
For a simplified atmosphere in two dimensions, we numerically solved the governing fluid equations to simulate the effect on dust nucleation and mantle growth as a result of the passage of an IGW. Furthermore, we derived an expression that relates the properties of the wave-induced cloud structures to observable parameters in order to deduce the atmospheric density.
Numerical simulations show that the $ρ, p, T$ variations caused by gravity waves lead to an increase of the nucleation rate by up to a factor 20, and an increase of the mantle growth rate by up to a factor 1.6, compared to their equilibrium values. An exploration of the wider parameter space shows that in absolute terms, the increase in nucleation due to IGW is stronger in cooler (T dwarfs) and TiO2-rich sub-stellar atmospheres. The relative increase, however, is greater in warmer (L dwarf) and TiO2-poor atmospheres due to conditions less suited for efficient nucleation at equilibrium. These variations lead to banded areas in which dust formation is much more pronounced, similar to the cloud structures observed on Earth.
We show that IGW in the atmosphere of sub-stellar objects can produce banded clouds structures similar to that observed on Earth. We propose a method with which potential observations of banded clouds could be used to estimate the atmospheric density of sub-stellar objects.
Condensation-inhibited convection in hydrogen-rich atmospheres: Stability against double-diffusive processes and thermal profiles for Jupiter, Saturn, Uranus, and Neptune
The Sonora Substellar Atmosphere Models. II. Cholla: A Grid of Cloud-free, Solar Metallicity Models in Chemical Disequilibrium for the JWST Era
系外行星和褐矮星的大气层通常显示出化学不平衡的迹象。在詹姆斯·韦伯太空望远镜时代，直接成像的系外行星的高分辨率光谱将允许更详细地描述其大气层，并允许系统测试这些大气层中偏离热化学平衡的化学物质的存在。限制这些大气中不平衡化学的存在作为参数的函数，如它们的有效温度和表面重力，将使我们能够更好地约束这些大气的物理学。本文是介绍索诺拉大气网格模型的一系列工作的一部分（Marley et al 2021，Morley et al in prep.）。在本文中，我们提出了一个网格的无云，太阳的金属丰度大气的棕矮星和宽分离的巨行星的关键分子物种，如CH 4，H2O，CO和NH3的不平衡。网格覆盖了Teff~[500 K，1300 K]，logg~[3.0，5.5]（cgs）和logKzz=2，4和7（cgs）的大气。我们研究了网格内不同参数对大气温度和成分分布的影响。我们讨论了它们对我们的模型大气的近红外颜色的影响，以及使用JWST对CH 4，H2O，CO和NH3的探测能力。我们将我们的模型与现有的MKO和斯皮策观测的棕矮星进行比较，并验证了T矮星大气的不平衡化学的重要性。最后，我们将讨论我们的模型如何帮助约束这些大气的垂直结构和化学成分。
Effects of density stratification on Rossby waves in deep atmospheres
JILA；Department of Astrophysical and Planetary Sciences, University of Colorado Boulder（科罗拉多大学博尔德分校天体物理与行星科学系）；Department of Applied Mathematics, University of Colorado Boulder（科罗拉多大学博尔德分校应用数学系）
Nonlinear internal waves breaking in stellar radiation zones. Parametrisation for the transport of angular momentum: bridging geophysical to stellar fluid dynamics
