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标题：A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b ⋆
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作者：E. Pallé ; A. Reiners ; K. Molaverdikhani 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2020
卷号：640
页码：1-9
DOI：10.1051/0004-6361/202038294
语种：English
出版社：EDP Sciences
摘要：Temperature inversion layers are predicted to be present in ultra-hot giant planet atmospheres. Although such inversion layers have recently been observed in several ultra-hot Jupiters, the chemical species responsible for creating the inversion remain unidentified. Here, we present observations of the thermal emission spectrum of an ultra-hot Jupiter, WASP-189b, at high spectral resolution using the HARPS-N spectrograph. Using the cross-correlation technique, we detect a strong Fe Isignal. The detected Fe Ispectral lines are found in emission, which is direct evidence of a temperature inversion in the planetary atmosphere. We further performed a retrieval on the observed spectrum using a forward model with an MCMC approach. When assuming a solar metallicity, the best-fit result returns a temperature of 4320−100+120K at the top of the inversion, which is significantly hotter than the planetary equilibrium temperature (2641 K). The temperature at the bottom of the inversion is determined as 2200−800+1000K. Such a strong temperature inversion is probably created by the absorption of atomic species like Fe I.
关键词：enplanets and satellites: atmospherestechniques: spectroscopicplanets and satellites: individual: WASP-189b