The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS
Full author list: 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.a,g,l, Garcia Muñoz, A.m, Hooton, M.J.f, Maxted, P.F.L.i, Morris, B.M., Van Grootel, V., Wilson, T.G., Alibert, Y., Alonso, R., Asquier, J., Bandy, T.f, Bárczy, T.q, Barrado, D.r, Barros, S.C.C.s,t, Baumjohann, W.b, 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.l, Guterman, P., Hasiba, J., Hernandez, E., Isaak, K., 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, N.C., Scandariato, G., Ségransan, D., Simon, A.E., Singh, V., Smith, A.M.S., Sordet, M., Sousa, S.G., Steller, M., Szabó, G.M., Thomas, N., Tschentscher, M., Udry, S., Viotto, V., Walter, I., Walton, N.A., Wildi, F., Wolter, D. ; 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. ; with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The Swiss participation to CHEOPS has been supported by the Swiss Space Office (SSO) in the framework of the Prodex Programme and the Activités Nationales Complémentaires (ANC), the Universities of Bern and Geneva as well as well as of the NCCR PlanetS and the Swiss National Science Foundation. M.L.E. acknowledges support from the Austrian Research Promotion Agency (FFG) under project 859724 "GRAPPA". Sz. Cs. thanks DFG Research Unit 2440: 'Matter Under Planetary Interior Conditions: High Pressure, Planetary, and Plasma Physics' for support. Sz. Cs. acknowledges support by DFG grants RA 714/14-1 within the DFG Schwerpunkt SPP 1992: "Exploring the Diversity of Extrasolar Planets". A.D.E. and D.E.H. acknowledge support from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (project FOUR ACES; grant agreement no. 724427). M.J.H. acknowledges the support of the Swiss National Fund under grant 200020_172746. The Spanish scientific participation in CHEOPS has been supported by the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grants ESP2016-80435-C2-1-R, ESP2016-80435-C2-2-R, ESP2017-87676-C5-1-R, PGC2018-098153-B-C31, PGC2018-098153-B-C33, and MDM-2017-0737 Unidad de Excelencia María de Maeztu–Centro de Astrobiología (INTA-CSIC), as well as by the Generalitat de Catalunya/CERCA programme. The MOC activities have been supported by the ESA contract No. 4000124370. This work was supported by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 – Programa Operacional Competitividade e Internacionalização by these grants: UID/FIS/04434/2019; UIDB/04434/2020; UIDP/04434/2020; PTDC/FIS-AST/32113/2017 & POCI-01-0145-FEDER-032113; PTDC/FIS-AST/28953/2017 & POCI-01-0145-FEDER-028953; PTDC/FIS-AST/28987/2017 & POCI-01-0145-FEDER-028987. S.C.C.B. and S.G.S. acknowledge support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004, IF/00028/2014/CP1215/CT0002. O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through Fundação para a Ciência e Tecnologia (FCT). The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Liege through an ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. M.G. is F.R.S.-FNRS Senior Research Associate. S.S. has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No 833925, project STAREX). Gy.S. acknowledges funding from the Hungarian National Research, Development and Innovation Office (NKFIH) grant GINOP-2.3.2-15-2016-00003 and K-119517. For Italy, CHEOPS activities have been supported by the Italian Space Agency, under the programs: ASI-INAF n. 2013-016-R.0 and ASI-INAF n. 2019-29-HH.0. The team at LAM acknowledges CNES funding for the development of the CHEOPS DRP, including grants 124378 for O.D. and 837319 for S.H. X.B., S.C., D.G., M.F. and J.L. acknowledge their role as an ESA-appointed CHEOPS science team members.