Recent observations of the super-Earth GJ?1214b show that it has a relatively featureless transmission spectrum. One suggestion is that these observations indicate that the planet's atmosphere is vertically compact, perhaps due to a water-rich composition that yields a large mean molecular weight. Another suggestion is that the atmosphere is hydrogen/helium-rich with clouds that obscure predicted absorption features. Previous models that incorporate clouds have included their effect without a strong physical motivation for their existence. Here, we present model atmospheres of GJ?1214b that include physically motivated clouds of two types. We model the clouds that are present in chemical equilibrium, as has been suggested to occur on brown dwarfs, which include KCl and ZnS for this planet. We also include clouds that form as a result of photochemistry, forming a hydrocarbon haze layer. We use a photochemical kinetics model to understand the vertical distribution and available mass of haze-forming molecules. We model both solar and enhanced-metallicity cloudy models and determine the cloud properties necessary to match observations. In enhanced-metallicity atmospheres, we find that the equilibrium clouds can match the observations of GJ?1214b if they are lofted high into the atmosphere and have a low sedimentation efficiency (f sed = 0.1). We find that models with a variety of hydrocarbon haze properties can match the observations. Particle sizes from 0.01 to 0.25 μm can match the transmission spectrum with haze-forming efficiencies as low as 1%-5%.
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机译：对超地球GJ？1214b的最新观察表明，它具有相对无特征的传输频谱。一个建议是，这些观察结果表明行星的大气在垂直方向上是紧凑的，这可能是由于富含水的成分产生了很大的平均分子量所致。另一个建议是，大气中富含氢气/氦气，并且云层遮盖了预期的吸收特征。以前包含云的模型已经包括了它们的影响，而没有强烈的物理动机来促使它们的存在。在这里，我们介绍了GJ？1214b的模型大气，其中包括两种类型的物理激励云。我们对存在于化学平衡中的云进行了建模，正如已经提出的那样，它出现在褐矮星上，包括该行星的KCl和ZnS。我们还包括由于光化学而形成的云，从而形成烃雾层。我们使用光化学动力学模型来了解雾状分子的垂直分布和可用质量。我们对太阳和增强金属的多云模型都进行了建模，并确定了与观测值匹配所必需的云属性。在增强金属的大气中，我们发现，如果平衡云被高高地放到大气中并且沉降效率较低（f sed = 0.1），则它们可以与GJ？1214b的观测值相匹配。我们发现具有各种烃雾度特性的模型可以与观测值相匹配。 0.01至0.25μm的粒径可以使透射光谱与雾形成效率低至1％-5％。
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