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Probing the tidal deformation and atmosphere of WASP-12b from phase curve observations

Presentation #203.01 in the session Star-Planet Interactions, Ultra-Hot Worlds.

Published onApr 03, 2024
Probing the tidal deformation and atmosphere of WASP-12b from phase curve observations

Ultra-hot Jupiters (UHJs) are subjected to strong stellar tidal forces and irradiation that allow us study the effects of extreme conditions on planets . The strong tidal interaction leads to the deformation of these planets from the usual spherical shapes. Since the response of a planet to the tidal force depends on its interior structure, detecting the tidal deformation provides insight into the interior structure of a planet through the measurement of its second-degree fluid Love number. Furthermore, the intense irradiation received by UHJs results in atmospheres that significantly differ from those of the Solar System gas giants, with high dayside temperatures that can lead to thermal dissociation of molecules such as water. Phase curve observations of UHJs provide an excellent opportunity to study these phenomena to better understand these extreme planets. In this talk, I will present the characterization of WASP-12b which stands out as one of the most irradiated UHJs, with an orbital period of only 1.09days around a G0 star of Teff = 6300K. The analysis combines observations from CHEOPS, TESS, and Spitzer to derive constraints on its tidal deformation and atmospheric properties. I will present the results from our phase curve analysis which show that WASP-12b is tidally deformed along the star-planet axis, enabling the reliable measurement of its Love number. Our results highlight the importance of modeling second-order effects in phase curves of UHJs which may bias the interpretation of observations, especially in the JWST era. I will also present our results on the atmospheric properties of the planet: constraining temperature–pressure profile, the day- and night-side fluxes, the hotspot offsets, and geometric albedos at the different passbands probed by the instruments. I will conclude with the prospects of JWST in probing the deformation, interior structure, and atmosphere of UHJs.

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