Transit spectroscopy is the most frequently used technique to reveal the atmospheric properties of exoplanets. At high resolution, it has the added advantage of resolving the small Doppler shift of spectral lines and, thus, the trace signal of the exoplanet atmosphere can be extracted separately. We obtained the transmission spectra of the extrasolar planet WASP-85Ab, a hot Jupiter in a 2.655-day orbit around a G5, V = 11.2 mag host star, observed by the high-resolution spectrograph ESPRESSO at the Very Large Telescope array for three transits. We present an analysis of the Rossiter-McLaughlin (RM) effect on WASP-85A and determine a spin-orbit angle λ = −16.155° −2.879 +2.916 , suggesting that the planet is in a nearly aligned orbit. Combining the transmission spectra of three nights, we tentatively detected H α and Call absorption with ⪆3 σ via direct visual inspection of the transmission spectra with the center-to-limb variation and the Rossiter-McLaughlin effects removed; these absorptions still remain visible after excluding the cores of these strong lines with a 0.1Å mask. These spectral signals appear likely to have originated from the planetary atmosphere, but we cannot fully exclude a stellar origin. Via the cross-correlation analysis of a set of atoms and molecules, Li I is marginally detected at the ∼4 σ level, suggesting that Li might be present in the atmosphere of WASP-85Ab.

Zewen Jiang

Wei Wang

Guo Chen

Fei Yan

Heather M. Cegla

Patricio Rojo

Yaqing Shi

Qinglin Ouyang

Meng Zhai

Yujuan Liu

Fei Zhao

Yuqin Chen

Astronomy and Astrophysics

ASTRONOMY & ASTROPHYSICS 是一本国际期刊，独立于用于获得结果的技术发表关于天文学和天体物理学（理论、观测和仪器）各个方面的论文。

Astronomy and Astrophysics is an international journal that focuses on various aspects of astronomy and astrophysics, including theory, observation, and instrumentation. The journal publishes high-quality academic papers independently of the techniques used to obtain research results.

《Astronomy and Astrophysics》是一本国际性期刊，专注于天文学和天体物理学的各个方面，包括理论、观测和仪器技术。该期刊独立于用于获得研究结果的技术，发表高质量的学术论文。

Category	Quartile
物理与天体物理	2
物理与天体物理, 天文与天体物理	2

Atmospheric composition of WASP-85Ab with ESPRESSO/VLT observations

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