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Title: The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS
Authors: Lendl, M.
Csizmadia, Sz.
Deline, A.
Fossati, L.
Kitzmann, D.
Heng, K.
Hoyer, S.
Salmon, S.
Benz, W.
Broeg, C.
Ehrenreich, D.
Malvasio, L.
Marafatto, L.
Michaelis, H.
Munari, M.
Nascimbeni, V.
Olofsson, G.
Ottacher, H.
Ottensamer, R.
Pagano, I.
Pallé, E.
Peter, G.
Pizza, D.
Piotto, G.
Pollacco, D.
Ratti, F.
Rauer, H.
Ragazzoni, R.
Rando, N.
Ribas, I.
Rieder, M.
Rohlfs, R.
Safa, F.
Santos, N. C.
Scandariato, G.
Ségransan, D.
Simón, A. E.
Singh, V.
Smith, A. M. S.
Sordet, Michael
Sousa, S. G.
Steller, M.
Szabó, Gy. M.
Thomas, N.
Tschentscher, M.
Udry, S.
Viotto, V.
Walter, I.
Walton, N. A.
Wildi, F.
Wolter, D.
Fortier, A.
Queloz, D.
Bonfanti, A.
Brandeker, A.
Collier Cameron, A.
Delrez, L.
García Muñoz, Antonio
Hooton, M. J.
Maxted, P. F. L.
Morris, B. M.
Van Grootel, V.
Wilson, T. G.
Alibert, Y.
Alonso, R.
Asquier, J.
Bandy, T.
Bárczy, T.
Barrado, D.
Barros, S. C. C.
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, M. B.
Deleuil, M.
Demangeon, O. D. S.
Demory, B. O.
Erikson, A.
Farinato, J.
Fridlund, M.
Futyan, D.
Gandolfi, D.
Gillon, M.
Guterman, P.
Hasiba, J.
Hernández, E.
Isaak, K. G.
Kiss, L.
Kuntzer, T.
Lecavelier des Etangs, A.
Lüftinger, T.
Laskar, J.
Lovis, C.
Magrin, D.
Keywords: Techniques: photometric;Planets and satellites: atmospheres;Planets and satellites: individual: WASP- 189 b
Issue Date: 9-Nov-2020
Publisher: EDP Sciences
DOI: 10.1051/0004-6361/202038677
Published version:
Citation: Astronomy and Astrophysics 643: A94
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.
Description: The photometric time series data are only available at the CDS via anonymous ftp to ( or via
E-ISSN: 1432-0746
ISSN: 0004-6361
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