Understanding the Depths of Brown Dwarfs and Giant Exoplanets: Modelling Substellar Atmospheres

该项目的主要目标是建立大气模型，以解释系外行星和褐矮星的观测结果。这两种类型的物体都是由相同的物理学描述的。褐矮星在测试各种物理过程方面特别有趣，因为这类物体目前比系外行星在观测上受到更好的限制。该项目将使用埃克塞特开发的最先进的工具，即一维大气代码ATMO和三维英国气象局环流模型。目标是对这些工具进行进一步的调整，以改进模型与观测结果的比较。第一个目标是关注褐矮星，提高我们对云和其他过程在这些寒冷大气中的作用的理解。最终目标是模拟各种各样的行星，从巨型行星到类地行星。特别是动力学和化学之间的耦合是正确解释观测结果的关键。目前，观测限制只适用于被其母恒星强烈辐射的系外行星，因为目前的观测技术倾向于探测距离其母恒星非常近的系外行星。因此，光化学过程在确定这些行星的大气成分、雾霾和/或云的性质以及光谱特征方面发挥着重要作用。在GCM中以一致的方式考虑这些过程是至关重要的，不仅对于指导未来系外地球上潜在生物特征的表征，而且对于对系外行星大气的一般理解和对现有观测结果的解释。

The main goal of the project is to develop atmosphere models to interpret observations ofexoplanets and brown dwarfs. Both types of objects are described by the same physics. Brown dwarfsare particularly interesting to test various physical processes because this family of object are currently much better observationally constrained than exoplanets. The project will involve the use of state-of-the-art tools develped in Exeter, namely a one-dimensionalatmospheric code ATMO and the three-dimensional UK Metoffice General Circulation Model. The goal is toperform further adaptations of these tools to improve the comparison of models with observations. One first aim is to focuson brown dwarfs and improve our understanding of the role of clouds and other processes in these cool atmospheres.The ultimate goal is to model a large variety of planets, from giant to Earth-like planets. In particular, the coupling between the dynamics and the chemistry is key for a correct interpretation of observations. For now, observational constraints are only available for exoplanets which are strongly irradiated by their parent star, as current observational techniques favour the detection of exoplanets located very close to their parent stars. Photochemical processes therefore play an important role in determining the atmospheric composition, properties of haze and/or clouds and spectroscopic signatures of these planets. Taking those processes into account in a consistent way within a GCM is critical, not only for guiding the future characterisation of potential biosignatures on exo-Earths, but also for the general understanding of exoplanet atmospheres and the interpretation of available observations.