The PEPSI Exoplanet Transit Survey (PETS). II. A Deep Search for Thermal Inversion Agents in KELT-20 b/MASCARA-2 b with Emission and Transmission Spectroscopy

Recent observations have shown that the atmospheres of ultrahot Jupiters (UHJs) commonly possess temperature inversions, where the temperature increases with increasing altitude. Nonetheless, which opacity sources are responsible for the presence of these inversions remains largely observationally u...

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Bibliographic Details
Published in:The Astronomical journal 2023-04, Vol.165 (4), p.157
Main Authors: Johnson, Marshall C., Wang 吉, Ji 王, Asnodkar, Anusha Pai, Bonomo, Aldo S., Gaudi, B. Scott, Henning, Thomas, Ilyin, Ilya, Keles, Engin, Malavolta, Luca, Mallonn, Matthias, Molaverdikhani, Karan, Nascimbeni, Valerio, Patience, Jennifer, Poppenhaeger, Katja, Scandariato, Gaetano, Schlawin, Everett, Shkolnik, Evgenya, Sicilia, Daniela, Sozzetti, Alessandro, Strassmeier, Klaus G., Veillet, Christian, Yan, Fei
Format: Article
Language:English
Subjects:
Astronomy
Emissions
Exoplanet astronomy
Exoplanet atmospheres
Extrasolar planets
Inversion
Inversions
Mixing ratio
Opacity
Searching
Spectroscopy
Temperature inversions
Temperature rise
Transmission spectroscopy
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Summary:Recent observations have shown that the atmospheres of ultrahot Jupiters (UHJs) commonly possess temperature inversions, where the temperature increases with increasing altitude. Nonetheless, which opacity sources are responsible for the presence of these inversions remains largely observationally unconstrained. We used LBT/PEPSI to observe the atmosphere of the UHJ KELT-20 b in both transmission and emission in order to search for molecular agents which could be responsible for the temperature inversion. We validate our methodology by confirming a previous detection of Fe i in emission at 16.9 σ . Our search for the inversion agents TiO, VO, FeH, and CaH results in non-detections. Using injection-recovery testing we set 4 σ upper limits upon the volume mixing ratios for these constituents as low as ∼1 × 10 −9 for TiO. For TiO, VO, and CaH, our limits are much lower than expectations from an equilibrium chemical model, while we cannot set constraining limits on FeH with our data. We thus rule out TiO and CaH as the source of the temperature inversion in KELT-20 b, and VO only if the line lists are sufficiently accurate.
ISSN:0004-6256
1538-3881
DOI:10.3847/1538-3881/acb7e2