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

大型行星和恒星物体中的动态大气是复杂的系统，但有一个特殊的基本方面超出了流体的描述：它们本质上是电性的，至少部分是。正如地球上的闪电是由雷雨云中积累在冰晶上的电荷突然释放而产生的，含有气溶胶和尘埃颗粒的活跃大气可能会产生强烈但短暂的电活动。这类事件对大气演化具有重大意义：自由电荷释放到中性大气中可以显著影响气体化学，因为这使得通过传统平衡过程无法获得的非平衡化学路径成为可能。此外，颗粒和气溶胶的充电对可以远程观测的辐射有进一步的影响。颗粒-颗粒相互作用可以产生大量非热自由电子，这些过程包括通过局部强表面电场释放颗粒电荷，以及改变在惯性带电粒子存在下运动的自由电子的能量分布。从棕矮星大气中探测到了异常的射电信号，这是探索这里描述的概念的理想工具。我们建议在充分考虑观测数据的情况下，从理论上、数值上探讨自由电荷和沉积电荷对棕矮星云大气的影响，包括自由电荷(电离过程，包括闪电)的产生，以及束流、带电气溶胶和独特化学物质的特征辐射特征。通过这样做，我们相信我们可以为这些迷人物体的特征和进化提供新的见解。

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.