Retrieval study of cool directly imaged exoplanet 51 Eri b
Retrieval study of cool directly imaged exoplanet 51 Eri b
复制标题
冷直接成像系外行星 51 Eri b 的反演研究
DOI：
10.1093/mnras/stad670
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发表时间：
2023
影响因子：
4.8
通讯作者：
Waldmann, Ingo P
中科院分区：
文献类型：
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作者：
Whiteford, Niall;Glasse, Alistair;Chubb, Katy L;Kitzmann, Daniel;Ray, Shrishmoy;Phillips, Mark W;Biller, Beth A;Palmer, Paul I;Rice, Ken;Waldmann, Ingo P
反演方法是一种强大的分析技术，可通过估算在前向模型中结合联合收割机以最佳拟合观测光谱的整体物理和化学性质，对系外行星大气进行建模，而且正越来越多地应用于直接成像的系外行星观测。我们已经改编了taurex 3，贝叶斯检索套件，近红外光谱直接成像的气体巨系外行星和褐矮星的分析。我们演示了taurex 3的适用性，亚恒星大气中的褐矮星基准GJ 570 D，这是与以前的检索研究一致的结果，同时也表现出系统的偏见与碱线的存在。我们还介绍了凉爽的系外行星51 Eri B的结果，免费的化学检索分析，这个对象的第一个应用程序，使用GPI和SPHERE的光谱观测。虽然我们的检索分析能够解释光谱和光度观测，而不采用云消光，我们得出结论，这可能是一个结果，采用灵活的温度-压力分布，能够模仿云的存在。我们提出了贝叶斯证据的氨检测与2.7σ的置信度，氨在直接成像的系外行星大气中的第一个迹象。这与这种分子存在于类似光谱类型的棕矮星中是一致的。我们证明了51 Eri B和GJ 570 D之间的化学相似性，其检索的分子丰度。最后，我们表明，51 Eri B的整体检索结论可以不同时，采用不同的光谱数据和建模组件，如温度，压力和云结构。
Retrieval methods are a powerful analysis technique for modelling exoplanetary atmospheres by estimating the bulk physical and chemical properties that combine in a forward model to best fit an observed spectrum, and they are increasingly being applied to observations of directly imaged exoplanets. We have adaptedtaurex3, the Bayesian retrieval suite, for the analysis of near-infrared spectrophotometry from directly imaged gas giant exoplanets and brown dwarfs. We demonstratetaurex3’s applicability to sub-stellar atmospheres by presenting results for brown dwarf benchmark GJ 570D which are consistent with previous retrieval studies, whilst also exhibiting systematic biases associated with the presence of alkali lines. We also present results for the cool exoplanet 51 Eri b, the first application of a free chemistry retrieval analysis to this object, using spectroscopic observations from GPI and SPHERE. While our retrieval analysis is able to explain spectroscopic and photometric observations without employing cloud extinction, we conclude this may be a result of employing a flexible temperature-pressure profile which is able to mimic the presence of clouds. We present Bayesian evidence for an ammonia detection with a 2.7σ confidence, the first indication of ammonia in a directly imaged exoplanetary atmosphere. This is consistent with this molecule being present in brown dwarfs of a similar spectral type. We demonstrate the chemical similarities between 51 Eri b and GJ 570D in relation to their retrieved molecular abundances. Finally, we show that overall retrieval conclusions for 51 Eri b can vary when employing different spectral data and modelling components, such as temperature–pressure and cloud structures.