ELECTRICALLY-ACTIVATED CLOUD CHEMISTRY IN THE ATMOSPHERES OF BROWN DWARFS AND EXOPLANETS

大型行星和恒星物体的动态大气是复杂的系统，但有一个特殊的基本方面，超越了流体的描述：它们本质上是电的，至少部分是电的。就像地球上的闪电是由雷云中冰晶上积累的电荷突然释放而产生的一样，含有气溶胶和尘埃颗粒的活跃大气可以产生强烈但短暂的电活动。这些事件对大气演变具有重要意义：释放到中性大气中的自由电荷可以显著影响气体化学，因为这使得通过常规平衡过程无法获得的非平衡化学途径成为可能。此外，颗粒和气溶胶的充电对可以远程观察到的辐射有向前的影响。颗粒-颗粒相互作用可以产生非热自由电子的群体，来自诸如经由局部强表面电场释放颗粒电荷的过程，以及来自改变在惯性带电粒子存在下移动的自由电子的能量分布。从褐矮星大气层中探测到了异常的无线电信号，这是探索这里描述的概念的理想工具。我们建议从理论上、数值上并在适当考虑观测数据的情况下，探索自由电荷和沉积电荷对褐矮星多云大气的影响，包括产生这种自由电荷（电离过程，包括闪电）以及光束、带电气溶胶和独特化学物质的特征辐射特征。这样做，我们相信我们可以为这些迷人物体的特征和演变提供新的见解。

The dynamic atmospheres in large, planetary and stellar objects are complex systems, but have a particular fundamental aspect that transcends the fluid description: they are electrical in nature, at least in part. Just as lightning on Earth is produced by the sudden release of electrical charge accumulated on ice crystals in thunder clouds, active atmospheres containing aerosols and dust particles can develop pockets of intense but transient electrical activity. Such events have a great significance for atmospheric evolution: the release of free charge into a neutral atmosphere can markedly affect the gaseous chemistry, since this makes possible non-equilibrium chemical pathways that are unavailable via conventional equilibrium processes. Moreover, the charging of grains and aerosols has an onward impact on the radiation that can be observed remotely. Grain-grain interactions can produce populations of non-thermal free electrons, from processes such as the release of grain charge via localised strong surface electric fields, and from modifying the energy distribution of free electrons moving in the presence of inertial, charged particles. Anomalous radio signatures have been detected from Brown Dwarf atmospheres, which are an ideal vehicle for exploring the concepts described here. We propose to explore, theoretically, numerically and with due consideration of observational data, the impact of free and deposited charge on the cloudy atmospheres of Brown Dwarfs, including the generation of such free charge (ionization processes, including lightning) and the characteristic radiation signature of beams, charged aerosols and unique chemistry. In so doing we believe that we can contribute fresh insight into the character and evolution of these fascinating objects.