Strong H2O and CO Emission Features in the Spectrum of KELT-20b Driven by Stellar UV Irradiation
AffiliationSteward Observatory, University of Arizona
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PublisherAmerican Astronomical Society
CitationFu, G., Sing, D. K., Lothringer, J. D., Deming, D., Ih, J., Kempton, E. M.-R., Malik, M., Komacek, T. D., Mansfield, M., & Bean, J. L. (2022). Strong H2O and CO Emission Features in the Spectrum of KELT-20b Driven by Stellar UV Irradiation. Astrophysical Journal Letters.
JournalAstrophysical Journal Letters
RightsCopyright © 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.
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AbstractKnow thy star, know thy planetary atmosphere. Every exoplanet with atmospheric measurements orbits around a star, and the stellar environment directly affects the planetary atmosphere. Here we present the emission spectrum of ultra-hot Jupiter KELT-20b which provides an observational link between host-star properties and planet atmospheric thermal structure. It is currently the only planet with thermal emission measurements in the T eq ∼ 2200 K range that orbits around an early A-type star. By comparing it with other similar ultra-hot Jupiters around FGK stars, we can better understand how different host-star types influence planetary atmospheres. The emission spectrum covers 0.6-4.5 μm with data from TESS, HST WFC3/G141, and Spitzer 4.5 μm channel. KELT-20b has a 1.4 μm water feature strength metric of = -0.097 0.02 and a blackbody brightness temperature difference of 528 K between WFC3/G141 (T b = 2402 14 K) and Spitzer 4.5 μm channel (T b = 2930 59 K). These very large H2O and CO emission features combined with the A-type host star make KELT-20b a unique planet among other similar hot Jupiters. The abundant FUV, NUV, and optical radiation from its host star (Teff = 8720 250 K) is expected to be the key that drives its strong thermal inversion and prominent emission features based on previous PHOENIX model calculations. © 2022. The Author(s). Published by the American Astronomical Society..
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Except where otherwise noted, this item's license is described as Copyright © 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.