论文标题
热木星黄蜂大气中氢化铬的证据
Evidence for chromium hydride in the atmosphere of Hot Jupiter WASP-31b
论文作者
论文摘要
语境。系外行星大气的表征在组成方面表现出广泛的多样性。热木星具有适当的温度可容纳金属化合物，应通过传输光谱检测到。目标。我们旨在通过测试各种化学物种来解释光谱，以检测热木星（特别是WASP-31B）的传播光谱中的外来物种。方法。我们使用贝叶斯检索框架taurex II对黄蜂31B的公开传输数据进行了重新分析。我们检索了25种物种的不透明性的各种组合，以确定适合观察到的光谱所需的最低集合。结果。我们报告了WASP-31B中氢化铬（CRH），H2O和K的光谱特征的证据。与没有任何签名的平面模型相比，首选仅CRH模型的统计意义为〜3.9 Sigma。在仅CRH+H2O组成的模型分别具有〜2.6 Sigma和〜3 Sigma置信度，分别在仅CRH和仅H2O的模型上。在H2O+CRH模型上发现了添加K的较弱证据，尽管在早期的研究中质疑与该签名相关的数据点的保真度。最后，在平坦模型上发现了碰撞诱导的吸收和瑞利散射斜率的包含。该分析提供了在热木星气氛中CRH签名的第一个证据。在检索到〜1481 K的温度下，黄蜂的大气足够热，可以容纳气态Cr的物种。检索到的丰度与热平衡化学的预测以及在L型棕色矮人气氛中发现的丰度非常吻合。但是，使用VLT fors2数据进行其他检索导致CRH的未检测。 JWST的未来覆盖范围有可能确认检测并发现其他CRH功能。
Context. The characterisation of exoplanet atmospheres has shown a wide diversity in compositions. Hot Jupiters have the appropriate temperatures to host metallic compounds, which should be detectable through transmission spectroscopy. Aims. We aim to detect exotic species in transmission spectra of hot Jupiters, specifically WASP-31b, by testing a variety of chemical species to explain the spectrum. Methods. We conduct a re-analysis of publicly available transmission data of WASP-31b using the Bayesian retrieval framework TauREx II. We retrieve various combinations of the opacities of 25 species to determine the minimum set needed to fit the observed spectrum. Results. We report evidence for the spectroscopic signatures of chromium hydride (CrH), H2O and K in WASP-31b. Compared to a flat model without any signatures, a CrH-only model is preferred with a statistical significance of ~3.9 sigma. A model consisting of both CrH+H2O is found with ~2.6 sigma and ~3 sigma confidence over a CrH-only and H2O-only model respectively. Weak evidence for the addition of K is found at ~2.2 sigma over the H2O+CrH model, although the fidelity of the data point associated with this signature was questioned in earlier studies. Finally, the inclusion of collision-induced absorption and a Rayleigh scattering slope is found with ~3.5 sigma confidence over a flat model. This analysis presents the first evidence for signatures of CrH in a hot Jupiter atmosphere. At a retrieved temperature of ~1481 K, the atmosphere of WASP-31b is hot enough to host gaseous Cr-bearing species. The retrieved abundances agree well with predictions from thermal equilibrium chemistry and with the abundance found in an L-type brown dwarf atmosphere. However, additional retrievals using VLT FORS2 data lead to a non-detection of CrH. Future coverage with JWST has the potential to confirm the detection and discover other CrH features.
