论文标题
在系外行星大气中鉴定二氧化碳
Identification of carbon dioxide in an exoplanet atmosphere
论文作者
论文摘要
二氧化碳（CO2）是一种关键的化学物种，在各种行星大气中发现。在系外行星的背景下，二氧化碳是金属富集的指标（即，元素比氦气重，也称为“金属性”），因此是热气巨人主要大气的形成过程。它也是在陆生外行星的次要气氛中检测到的最有前途的物种之一。先前用Spitzer空间望远镜对过境行星进行的光度测量表明，由于缺乏明确的光谱识别，但由于缺乏明确的光谱识别，但没有产生确定的检测。在这里，我们介绍了从JWST获得的传输光谱观测值（作为早期发行科学计划（ERS）的一部分）中的气体巨型系外行星WASP-39B大气中的CO2的检测。这项研究中使用的数据在波长中跨度为3.0至5.5μm，并在4.3μm处显示出显着的CO2吸收特征（26σ显着性）。总频谱与一维太阳金属度模型良好匹配，这些模型假设辐射性传染性 - 热化学平衡并具有中等的云不透明度。这些模型预测，除了二氧化碳之外，大气还应具有水，一氧化碳和硫化氢，但甲烷却很少。此外，我们还暂时检测到附近4.0μm附近的较小的吸收特征，这些吸收特征并未由这些模型再现。
Carbon dioxide (CO2) is a key chemical species that is found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the metal enrichment (i.e., elements heavier than helium, also called "metallicity"), and thus formation processes of the primary atmospheres of hot gas giants. It is also one of the most promising species to detect in the secondary atmospheres of terrestrial exoplanets. Previous photometric measurements of transiting planets with the Spitzer Space Telescope have given hints of the presence of CO2 but have not yielded definitive detections due to the lack of unambiguous spectroscopic identification. Here we present the detection of CO2 in the atmosphere of the gas giant exoplanet WASP-39b from transmission spectroscopy observations obtained with JWST as part of the Early Release Science Program (ERS). The data used in this study span 3.0 to 5.5 μm in wavelength and show a prominent CO2 absorption feature at 4.3 μm (26σ significance). The overall spectrum is well matched by one-dimensional, 10x solar metallicity models that assume radiative-convective-thermochemical equilibrium and have moderate cloud opacity. These models predict that the atmosphere should have water, carbon monoxide, and hydrogen sulfide in addition to CO2, but little methane. Furthermore, we also tentatively detect a small absorption feature near 4.0 μm that is not reproduced by these models.
