论文标题
与下一代设施的K2-18 B的大气组成
Disentangling Atmospheric Compositions of K2-18 b with Next Generation Facilities
论文作者
论文摘要
对行星K2-18b的最新分析表明，其大气中存在水蒸气。尽管H2O检测很重要，但Hubble空间望远镜（HST）WFC3频谱提出了三种非常不同性质的解决方案，它们可以平均匹配数据。这三种溶液是一种原发性的多云大气，具有痕迹的水蒸气（云彩亚北极果），这是H2O（ICY/Water World）和/或不可发现的气体（例如N2（Super-Arthth））的次级大气（高达50％的体积混合率）。另外，通过目前可用的观测值无法研究大气压力和液体/固体表面的可能存在。 在本文中，我们使用了Tsiaras等人的最佳拟合参数。 （2019年）建立詹姆斯·韦伯太空望远镜（JWST）和三种情况的Ariel模拟。我们已经调查了18个检索案例，其中包括两个观察者的三种情况和不同的观察策略。检索结果表明，二十个合并的过境应该足以使Ariel任务解散这三种情况，而如果将Niriss和NirSpec数据组合在一起，JWST将仅需要两个转移。这使K2-18B成为设施大气随访的理想目标，并突出了下一代空间红外观测站的能力，可提供低质量行星的完整图片。
Recent analysis of the planet K2-18b has shown the presence of water vapour in its atmosphere. While the H2O detection is significant, the Hubble Space Telescope (HST) WFC3 spectrum suggests three possible solutions of very different nature which can equally match the data. The three solutions are a primary cloudy atmosphere with traces of water vapour (cloudy sub-Neptune), a secondary atmosphere with a substantial amount (up to 50% Volume Mixing Ratio) of H2O (icy/water world) and/or an undetectable gas such as N2 (super-Earth). Additionally, the atmospheric pressure and the possible presence of a liquid/solid surface cannot be investigated with currently available observations. In this paper we used the best fit parameters from Tsiaras et al. (2019) to build James Webb Space Telescope (JWST) and Ariel simulations of the three scenarios. We have investigated 18 retrieval cases, which encompass the three scenarios and different observational strategies with the two observatories. Retrieval results show that twenty combined transits should be enough for the Ariel mission to disentangle the three scenarios, while JWST would require only two transits if combining NIRISS and NIRSpec data. This makes K2-18b an ideal target for atmospheric follow-ups by both facilities and highlights the capabilities of the next generation of space-based infrared observatories to provide a complete picture of low mass planets.
