Lendl, M, Csizmadia, S, Deline, A, Fossati, L, Kitzmann, D, Heng, K, Hoyer, S, Salmon, S, Benz, W, Broeg, C, Ehrenreich, D, Fortier, A, Queloz, D, Bonfanti, A, Brandeker, A, Collier Cameron, A, Delrez, L, Garcia Mu noz, A, Hooton, MJ, Maxted, PFL ORCID: https://orcid.org/0000-0003-3794-1317, Morris, BM, Van Grootel, V, Wilson, TG, Alibert, Y, Alonso, R, Asquier, J, Bandy, T, Bárczy, T, Barrado, D, Barros, SCC, Baumjohann, W, Beck, M, Beck, T, Bekkelien, A, Bergomi, M, Billot, N, Biondi, F, Bonfils, X, Bourrier, V, Busch, M-D, Cabrera, J, Cessa, V, Charnoz, S, Chazelas, B, Corral Van Damme, C, Davies, MB, Deleuil, M, Demangeon, ODS, Demory, B-O, Erikson, A, Farinato, J, Fridlund, M, Futyan, D, Gandolfi, D, Gillon, M, Guterman, P, Hasiba, J, Hernandez, E, Isaak, KG, Kiss, L, Kuntzer, T, Lecavelier des Etangs, A, Lüftinger, T, Laskar, J, Lovis, C, Magrin, D, Malvasio, L, Marafatto, L, Michaelis, H, Munari, M, Nascimbeni, V, Olofsson, G, Ottacher, H, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piazza, D, Piotto, G, Pollacco, D, Ratti, F, Rauer, H, Ragazzoni, R, Rando, N, Ribas, I, Rieder, M, Rohlfs, R, Safa, F, Santos, NC, Scandariato, G, Ségransan, D, Simon, AE, Singh, V, Smith, AMS, Sordet, M, Sousa, SG, Steller, M, Szabó, GM, Thomas, N, Tschentscher, M, Udry, S, Viotto, V, Walter, I, Walton, NA, Wildi, F and Wolter, D (2020) The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS. Astronomy and Astrophysics, 643.

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Abstract

The CHEOPS space mission dedicated to exoplanet follow-up was launched in December 2019, equipped with the capacity to perform photometric measurements at the 20 ppm level. As CHEOPS carries out its observations in a broad optical passband, it can provide insights into the reflected light from exoplanets and constrain the short-wavelength thermal emission for the hottest of planets by observing occultations and phase curves. Here, we report the first CHEOPS observation of an occultation, namely, that of the hot Jupiter WASP-189 b, a MP ≈ 2MJ planet orbiting an A-type star. We detected the occultation of WASP-189 b at high significance in individual measurements and derived an occultation depth of dF = 87.9 ± 4.3 ppm based on four occultations. We compared these measurements to model predictions and we find that they are consistent with an unreflective atmosphere heated to a temperature of 3435 ± 27 K, when assuming inefficient heat redistribution. Furthermore, we present two transits of WASP-189 b observed by CHEOPS. These transits have an asymmetric shape that we attribute to gravity darkening of the host star caused by its high rotation rate. We used these measurements to refine the planetary parameters, finding a ~25% deeper transit compared to the discovery paper and updating the radius of WASP-189 b to 1.619 ± 0.021RJ. We further measured the projected orbital obliquity to be λ = 86.4−4.4+2.9°, a value that is in good agreement with a previous measurement from spectroscopic observations, and derived a true obliquity of Ψ = 85.4 ± 4.3°. Finally, we provide reference values for the photometric precision attained by the CHEOPS satellite: for the V = 6.6 mag star, and using a 1-h binning, we obtain a residual RMS between 10 and 17 ppm on the individual light curves, and 5.7 ppm when combining the four visits.

Item Type: Article
Uncontrolled Keywords: techniques: photometric – planets and satellites: atmospheres – planets and satellites: individual: WASP-189 b
Subjects: Q Science > QB Astronomy > QB799 Stars
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Symplectic
Date Deposited: 16 Dec 2020 14:38
Last Modified: 16 Mar 2021 12:16
URI: https://eprints.keele.ac.uk/id/eprint/9017

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