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arXiv · 2001.07196

Detection of neutral atomic species in the ultra-hot jupiter WASP-121b

Samuel H. C. Cabot·Nikku Madhusudhan·Luis Welbanks·Anjali Piette·Siddharth Gandhi
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Abstract

The class of ultra-hot Jupiters comprises giant exoplanets undergoing intense irradiation from their host stars. They have proved to be a particularly interesting population for their orbital and atmospheric properties. One such planet, WASP-121~b, is in a highly misaligned orbit close to its Roche limit, and its atmosphere exhibits a thermal inversion. These properties make WASP-121~b an interesting target for additional atmospheric characterization. In this paper, we present analysis of archival high-resolution optical spectra obtained during transits of WASP-121~b. Artifacts from the Rossiter-McLaughlin effect and Center-to-Limb Variation are deemed negligible. However, we discuss scenarios where these effects warrant more careful treatment by modeling the WASP-121 system and varying its properties. We report a new detection of atmospheric absorption from H$\alpha$ in the planet with a transit depth of $1.87\pm0.11\%$. We further confirm a previous detection of the Na I doublet, and report a new detection of Fe I via cross-correlation with a model template. We attribute the H$\alpha$ absorption to an extended Hydrogen atmosphere, potentially undergoing escape, and the Fe I to equilibrium chemistry at the planetary photosphere. These detections help to constrain the composition and chemical processes in the atmosphere of WASP-121~b.

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Samuel H. C. Cabot, Nikku Madhusudhan, Luis Welbanks, Anjali Piette, Siddharth Gandhi. 2020-01-20. Detection of neutral atomic species in the ultra-hot jupiter WASP-121b. https://doi.org/10.1093/mnras/staa748

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