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  • 1. Benz, W.
    et al.
    Broeg, C.
    Fortier, A.
    Rando, N.
    Beck, T.
    Beck, M.
    Queloz, D.
    Ehrenreich, D.
    Maxted, P. F. L.
    Isaak, K. G.
    Billot, N.
    Alibert, Y.
    Alonso, R.
    Antonio, C.
    Asquier, J.
    Bandy, T.
    Barczy, T.
    Barrado, D.
    Barros, S. C. C.
    Baumjohann, W.
    Bekkelien, A.
    Bergomi, M.
    Biondi, F.
    Bonfils, X.
    Borsato, L.
    Brandeker, Alexis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Busch, M.-D.
    Cabrera, J.
    Cessa, V.
    Charnoz, S.
    Chazelas, B.
    Collier Cameron, A.
    Corral Van Damme, C.
    Cortes, D.
    Davies, M. B.
    Deleuil, M.
    Deline, A.
    Delrez, L.
    Demangeon, O.
    Demory, B. O.
    Erikson, A.
    Farinato, J.
    Fossati, L.
    Fridlund, M.
    Futyan, D.
    Gandolfi, D.
    Garcia Munoz, A.
    Gillon, M.
    Guterman, P.
    Gutierrez, A.
    Hasiba, J.
    Heng, K.
    Hernandez, E.
    Hoyer, S.
    Kiss, L. L.
    Kovacs, Z.
    Kuntzer, T.
    Laskar, J.
    Lecavelier des Etangs, A.
    Lendl, M.
    Lopez, A.
    Lora, I.
    Lovis, C.
    Lueftinger, T.
    Magrin, D.
    Malvasio, L.
    Marafatto, L.
    Michaelis, H.
    de Miguel, D.
    Modrego, D.
    Munari, M.
    Nascimbeni, V.
    Olofsson, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Ottacher, H.
    Ottensamer, R.
    Pagano, I.
    Palacios, R.
    Pall, E.
    Peter, G.
    Piazza, D.
    Piotto, G.
    Pizarro, A.
    Pollaco, D.
    Ragazzoni, R.
    Ratti, F.
    Rauer, H.
    Ribas, I.
    Rieder, M.
    Rohlfs, R.
    Safa, F.
    Salatti, M.
    Santos, N. C.
    Scandariato, G.
    Segransan, D.
    Simon, A. E.
    Smith, A. M. S.
    Sordet, M.
    Sousa, S. G.
    Steller, M.
    Szabo, G. M.
    Szoke, J.
    Thomas, N.
    Tschentscher, M.
    Udry, S.
    Van Grootel, V.
    Viotto, V.
    Walter, I.
    Walton, N. A.
    Wildi, F.
    Wolter, D.
    The CHEOPS mission2021Inngår i: Experimental astronomy, ISSN 0922-6435, E-ISSN 1572-9508, Vol. 51, s. 109-151Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The CHaracterising ExOPlanet Satellite (CHEOPS) was selected on October 19, 2012, as the first small mission (S-mission) in the ESA Science Programme and successfully launched on December 18, 2019, as a secondary passenger on a Soyuz-Fregat rocket from Kourou, French Guiana. CHEOPS is a partnership between ESA and Switzerland with important contributions by ten additional ESA Member States. CHEOPS is the first mission dedicated to search for transits of exoplanets using ultrahigh precision photometry on bright stars already known to host planets. As a follow-up mission, CHEOPS is mainly dedicated to improving, whenever possible, existing radii measurements or provide first accurate measurements for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys. The expected photometric precision will also allow CHEOPS to go beyond measuring only transits and to follow phase curves or to search for exo-moons, for example. Finally, by unveiling transiting exoplanets with high potential for in-depth characterisation, CHEOPS will also provide prime targets for future instruments suited to the spectroscopic characterisation of exoplanetary atmospheres. To reach its science objectives, requirements on the photometric precision and stability have been derived for stars with magnitudes ranging from 6 to 12 in the V band. In particular, CHEOPS shall be able to detect Earth-size planets transiting G5 dwarf stars (stellar radius of 0.9R(circle dot)) in the magnitude range 6 <= V <= 9 by achieving a photometric precision of 20 ppm in 6 hours of integration time. In the case of K-type stars (stellar radius of 0.7R(circle dot)) of magnitude in the range 9 <= V <= 12, CHEOPS shall be able to detect transiting Neptune-size planets achieving a photometric precision of 85 ppm in 3 hours of integration time. This precision has to be maintained over continuous periods of observation for up to 48 hours. This precision and stability will be achieved by using a single, frame-transfer, back-illuminated CCD detector at the focal plane assembly of a 33.5 cm diameter, on-axis Ritchey-Chretien telescope. The nearly 275 kg spacecraft is nadir-locked, with a pointing accuracy of about 1 arcsec rms, and will allow for at least 1 Gbit/day downlink. The sun-synchronous dusk-dawn orbit at 700 km altitude enables having the Sun permanently on the backside of the spacecraft thus minimising Earth stray light. A mission duration of 3.5 years in orbit is foreseen to enable the execution of the science programme. During this period, 20% of the observing time is available to the wider community through yearly ESA call for proposals, as well as through discretionary time approved by ESA's Director of Science. At the time of this writing, CHEOPS commissioning has been completed and CHEOPS has been shown to fulfill all its requirements. The mission has now started the execution of its science programme.

  • 2. Borsato, L.
    et al.
    Piotto, G.
    Gandolfi, D.
    Nascimbeni, V
    Lacedelli, G.
    Marzari, F.
    Billot, N.
    Maxted, P. F. L.
    Sousa, S.
    Cameron, A. C.
    Bonfanti, A.
    Wilson, T. G.
    Serrano, L. M.
    Garai, Z.
    Alibert, Y.
    Alonso, R.
    Asquier, J.
    Bárczy, T.
    Bandy, T.
    Barrado, D.
    Barros, S. C. C.
    Baumjohann, W.
    Beck, M.
    Beck, T.
    Benz, W.
    Bonfils, X.
    Brandeker, Alexis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Broeg, C.
    Cabrera, J.
    Charnoz, S.
    Csizmadia, S.
    Davies, M. B.
    Deleuil, M.
    Delrez, L.
    Demangeon, O.
    Demory, B-O
    des Etangs, A. L.
    Ehrenreich, D.
    Erikson, A.
    Escudé, G. A.
    Fortier, A.
    Fossati, L.
    Fridlund, M.
    Gillon, M.
    Guedel, M.
    Hasiba, J.
    Heng, K.
    Hoyer, S.
    Isaak, K. G.
    Kiss, L.
    Kopp, E.
    Laskar, J.
    Lendl, M.
    Lovis, C.
    Magrin, D.
    Munari, M.
    Olofsson, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Ottensamer, R.
    Pagano, I
    Pallé, E.
    Peter, G.
    Pollacco, D.
    Queloz, D.
    Ragazzoni, R.
    Rando, N.
    Rauer, H.
    Ribas, I
    Ségransan, D.
    Santos, N. C.
    Scandariato, G.
    Simon, A.
    Smith, A. M. S.
    Steller, M.
    Szabó, G.
    Thomas, N.
    Udry, S.
    Van Grootel, V.
    Walton, N.
    Exploiting timing capabilities of the CHEOPS mission with warm-Jupiter planets2021Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 506, nr 3, s. 3810-3830Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present 17 transit light curves of seven known warm-Jupiters observed with the CHaracterising ExOPlanet Satellite (CHEOPS). The light curves have been collected as part of the CHEOPS Guaranteed Time Observation (GTO) program that searches for transit-timing variation (TTV) of warm-Jupiters induced by a possible external perturber to shed light on the evolution path of such planetary systems. We describe the CHEOPS observation process, from the planning to the data analysis. In this work, we focused on the timing performance of CHEOPS, the impact of the sampling of the transit phases, and the improvement we can obtain by combining multiple transits together. We reached the highest precision on the transit time of about 13–16 s for the brightest target (WASP-38, G = 9.2) in our sample. From the combined analysis of multiple transits of fainter targets with G ≥ 11, we obtained a timing precision of ∼2 min. Additional observations with CHEOPS, covering a longer temporal baseline, will further improve the precision on the transit times and will allow us to detect possible TTV signals induced by an external perturber.

  • 3. Delrez, Laetitia
    et al.
    Ehrenreich, David
    Alibert, Yann
    Bonfanti, Andrea
    Borsato, Luca
    Fossati, Luca
    Hooton, Matthew J.
    Hoyer, Sergio
    Pozuelos, Francisco J.
    Salmon, Sébastien
    Sulis, Sophia
    Wilson, Thomas G.
    Adibekyan, Vardan
    Bourrier, Vincent
    Brandeker, Alexis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Charnoz, Sébastien
    Deline, Adrien
    Guterman, Pascal
    Haldemann, Jonas
    Hara, Nathan
    Oshagh, Mahmoudreza
    Sousa, Sergio G.
    Van Grootel, Valérie
    Alonso, Roi
    Anglada-Escudé, Guillem
    Bárczy, Tamás
    Barrado, David
    Barros, Susana C. C.
    Baumjohann, Wolfgang
    Beck, Mathias
    Bekkelien, Anja
    Benz, Willy
    Billot, Nicolas
    Bonfils, Xavier
    Broeg, Christopher
    Cabrera, Juan
    Collier Cameron, Andrew
    Davies, Melvyn B.
    Deleuil, Magali
    Delisle, Jean-Baptiste
    Demangeon, Olivier D. S.
    Demory, Brice-Olivier
    Erikson, Anders
    Fortier, Andrea
    Fridlund, Malcolm
    Futyan, David
    Gandolfi, Davide
    Garcia Muñoz, Antonio
    Gillon, Michael
    Guedel, Manuel
    Heng, Kevin
    Kiss, László
    Laskar, Jacques
    Lecavelier des Etangs, Alain
    Lendl, Monika
    Lovis, Christophe
    Maxted, Pierre F. L.
    Nascimbeni, Valerio
    Olofsson, Göran
    Osborn, Hugh P.
    Pagano, Isabella
    Pallé, Enric
    Piotto, Giampaolo
    Pollacco, Don
    Queloz, Didier
    Rauer, Heike
    Ragazzoni, Roberto
    Ribas, Ignasi
    Santos, Nuno C.
    Scandariato, Gaetano
    Ségransan, Damien
    Simon, Attila E.
    Smith, Alexis M. S.
    Steller, Manfred
    Szabó, Gyula M.
    Thomas, Nicolas
    Udry, Stéphane
    Walton, Nicholas A.
    Transit detection of the long-period volatile-rich super-Earth nu(2) Lupi d with CHEOPS2021Inngår i: Nature Astronomy, E-ISSN 2397-3366, nr 5, s. 775-787Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Exoplanets transiting bright nearby stars are key objects for advancing our knowledge of planetary formation and evolution. The wealth of photons from the host star gives detailed access to the atmospheric, interior and orbital properties of the planetary companions. nu(2) Lupi (HD 136352) is a naked-eye (V = 5.78) Sun-like star that was discovered to host three low-mass planets with orbital periods of 11.6, 27.6 and 107.6 d via radial-velocity monitoring(1). The two inner planets (b and c) were recently found to transit(2), prompting a photometric follow-up by the brand new Characterising Exoplanets Satellite (CHEOPS). Here, we report that the outer planet d is also transiting, and measure its radius and mass to be 2.56 +/- 0.09 R-circle plus and 8.82 +/- 0.94 M-circle plus, respectively. With its bright Sun-like star, long period and mild irradiation (similar to 5.7 times the irradiation of Earth), nu(2) Lupi d unlocks a completely new region in the parameter space of exoplanets amenable to detailed characterization. We refine the properties of all three planets: planet b probably has a rocky mostly dry composition, while planets c and d seem to have retained small hydrogen-helium envelopes and a possibly large water fraction. This diversity of planetary compositions makes the nu(2) Lupi system an excellent laboratory for testing formation and evolution models of low-mass planets.

  • 4. Hooton, M. J.
    et al.
    Hoyer, S.
    Kitzmann, D.
    Morris, B. M.
    Smith, A. M. S.
    Collier Cameron, A.
    Futyan, D.
    Maxted, P. F. L.
    Queloz, D.
    Demory, B.-O.
    Heng, K.
    Lendl, M.
    Cabrera, J.
    Csizmadia, Sz.
    Deline, A.
    Parviainen, H.
    Salmon, S.
    Sulis, S.
    Wilson, T. G.
    Bonfanti, A.
    Brandeker, Alexis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Demangeon, O. D. S.
    Oshagh, M.
    Persson, C. M.
    Scandariato, G.
    Alibert, Y.
    Alonso, R.
    Anglada Escude, G.
    Barczy, T.
    Barrado, D.
    Barros, S. C. C.
    Baumjohann, W.
    Beck, M.
    Beck, T.
    Benz, W.
    Billot, N.
    Bonfils, X.
    Bourrier, V.
    Broeg, C.
    Busch, M.-D.
    Charnoz, S.
    Davies, M. B.
    Deleuil, M.
    Delrez, L.
    Ehrenreich, D.
    Erikson, A.
    Farinato, J.
    Fortier, A.
    Fossati, L.
    Fridlund, M.
    Gandolfi, D.
    Gillon, M.
    Gudel, M.
    Isaak, K. G.
    Jones, K.
    Kiss, L.
    Laskar, J.
    Lecavelier des Etangs, A.
    Lovis, C.
    Luntzer, A.
    Magrin, D.
    Nascimbeni, V.
    Olofsson, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Ottensamer, R.
    Pagano, I.
    Palle, E.
    Peter, G.
    Piotto, G.
    Pollacco, D.
    Ragazzoni, R.
    Rando, N.
    Ratti, F.
    Rauer, H.
    Ribas, I.
    Santos, N. C.
    Segransan, D.
    Simon, A. E.
    Sousa, S. G.
    Steller, M.
    Szabo, Gy. M.
    Thomas, N.
    Udry, S.
    Ulmer, B.
    Van Grootel, V.
    Walton, N. A.
    Spi-OPS: Spitzer and CHEOPS confirm the near-polar orbit of MASCARA-1 b and reveal a hint of dayside reflection2022Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 658, artikkel-id A75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. The light curves of tidally locked hot Jupiters transiting fast-rotating, early-type stars are a rich source of information about both the planet and star, with full-phase coverage enabling a detailed atmospheric characterisation of the planet. Although it is possible to determine the true spin-orbit angle Ψ - a notoriously difficult parameter to measure - from any transit asymmetry resulting from gravity darkening induced by the stellar rotation, the correlations that exist between the transit parameters have led to large disagreements in published values of Ψ for some systems.

    Aims. We aimed to study these phenomena in the light curves of the ultra-hot Jupiter MASCARA-1 b, which is characteristically similar to well-studied contemporaries such as KELT-9 b and WASP-33 b.

    Methods. We obtained optical CHaracterising ExOPlanet Satellite (CHEOPS) transit and occultation light curves of MASCARA-1 b, and analysed them jointly with a Spitzer/IRAC 4.5 µm full-phase curve to model the asymmetric transits, occultations, and phasedependent flux modulation. For the latter, we employed a novel physics-driven approach to jointly fit the phase modulation by generating a single 2D temperature map and integrating it over the two bandpasses as a function of phase to account for the differing planet-star flux contrasts. The reflected light component was modelled using the general ab initio solution for a semi-infinite atmosphere.

    Results. When fitting the CHEOPS and Spitzer transits together, the degeneracies are greatly diminished and return results consistent with previously published Doppler tomography. Placing priors informed by the tomography achieves even better precision, allowing a determination of Ψ = 72.1(-2.4)(+2.5) deg. From the occultations and phase variations, we derived dayside and nightside temperatures of 3062(-68)(+66) K and 1720 +/- 330 K, respectively. Our retrieval suggests that the dayside emission spectrum closely follows that of a blackbody. As the CHEOPS occultation is too deep to be attributed to blackbody flux alone, we could separately derive geometric albedo A(g) = 0.171(-0.068)(+0.066) and spherical albedo A(s) = 0.266(-0.100)(+0.097) from the CHEOPS data, and Bond albedo AB = 0.057(-0.101)(+0.083) from the Spitzer phase curve. Although small, the A(g) and A(s) indicate that MASCARA-1 b is more reflective than most other ultra-hot Jupiters, where H- absorption is expected to dominate.

    Conclusions. Where possible, priors informed by Doppler tomography should be used when fitting transits of fast-rotating stars, though multi-colour photometry may also unlock an accurate measurement of Ψ. Our approach to modelling the phase variations at different wavelengths provides a template for how to separate thermal emission from reflected light in spectrally resolved James Webb Space Telescope phase curve data.

  • 5. Leleu, A.
    et al.
    Alibert, Y.
    Hara, N. C.
    Hooton, M. J.
    Wilson, T. G.
    Robutel, P.
    Delisle, J.-B.
    Laskar, J.
    Hoyer, S.
    Lovis, C.
    Bryant, E. M.
    Ducrot, E.
    Cabrera, J.
    Delrez, L.
    Acton, J. S.
    Adibekyan, V.
    Allart, R.
    Allende Prieto, C.
    Alonso, R.
    Alves, D.
    Anderson, D. R.
    Angerhausen, D.
    Anglada Escude, G.
    Asquier, J.
    Barrado, D.
    Barros, S. C. C.
    Baumjohann, W.
    Bayliss, D.
    Beck, M.
    Beck, T.
    Bekkelien, A.
    Benz, W.
    Billot, N.
    Bonfanti, A.
    Bonfils, X.
    Bouchy, F.
    Bourrier, V.
    Boue, G.
    Brandeker, Alexis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Broeg, C.
    Buder, M.
    Burdanov, A.
    Burleigh, M. R.
    Barczy, T.
    Cameron, A. C.
    Chamberlain, S.
    Charnoz, S.
    Cooke, B. F.
    Corral Van Damme, C.
    Correia, A. C. M.
    Cristiani, S.
    Damasso, M.
    Davies, M. B.
    Deleuil, M.
    Demangeon, O. D. S.
    Demory, B.-O.
    Di Marcantonio, P.
    Di Persio, G.
    Dumusque, X.
    Ehrenreich, D.
    Erikson, A.
    Figueira, P.
    Fortier, A.
    Fossati, L.
    Fridlund, M.
    Futyan, D.
    Gandolfi, D.
    Garcia Munoz, A.
    Garcia, L. J.
    Gill, S.
    Zapatero Osorio, M. R.
    Gillen, E.
    Gillon, M.
    Goad, M. R.
    Gonzalez Hernandez, J.
    Guedel, M.
    Haldemann, J.
    Henderson, B.
    Heng, K.
    Hogan, A. E.
    Isaak, K.
    Jehin, E.
    Jenkins, J. S.
    Jordan, A.
    Kiss, L.
    Kristiansen, M. H.
    Lam, K.
    Lavie, B.
    Lecavelier des Etangs, A.
    Lendl, M.
    Lillo-Box, J.
    Lo Curto, G.
    Magrin, D.
    Martins, C. J. A. P.
    Maxted, P. F. L.
    McCormac, J.
    Mehner, A.
    Micela, G.
    Molaro, P.
    Moyano, M.
    Murray, C. A.
    Nascimbeni, V.
    Nunes, N. J.
    Olofsson, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Osborn, H. P.
    Oshagh, M.
    Ottensamer, R.
    Pagano, I.
    Palle, E.
    Pedersen, P. P.
    Pepe, F. A.
    Persson, C. M.
    Peter, G.
    Piotto, G.
    Polenta, G.
    Pollacco, D.
    Poretti, E.
    Pozuelos, F. J.
    Queloz, D.
    Ragazzoni, R.
    Rando, N.
    Ratti, F.
    Rauer, H.
    Raynard, L.
    Rebolo, R.
    Reimers, C.
    Ribas, I.
    Santos, N. C.
    Scandariato, G.
    Schneider, J.
    Sebastian, D.
    Sestovic, M.
    Simon, A. E.
    Smith, A. M. S.
    Sousa, S. G.
    Sozzetti, A.
    Steller, M.
    Suarez Mascareno, A.
    Szabo, Gy M.
    Segransan, D.
    Thomas, N.
    Thompson, S.
    Tilbrook, R. H.
    Triaud, A.
    Turner, O.
    Udry, S.
    Van Grootel, V.
    Venus, H.
    Verrecchia, F.
    Vines, J.
    Walton, N. A.
    West, R. G.
    Wheatley, P. J.
    Wolter, D.
    Six transiting planets and a chain of Laplace resonances in TOI-1782021Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 649, artikkel-id A26Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152(-0.070)(+0.073)</textual-form> 1.152-0.070+0.073 to 2.87(-0.13)(+0.14)</textual-form> 2.87-0.13+0.14 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02(-0.23)(+0.28)</textual-form> 1.02-0.23+0.28 to 0.177(-0.061)(+0.055)</textual-form> 0.177-0.061+0.055 times the Earth's density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.

  • 6. Lendl, M.
    et al.
    Csizmadia, Sz.
    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, Alexis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Cameron, A. Collier
    Delrez, L.
    Garcia Muñoz, A.
    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.
    Van Damme, C. Corral
    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.
    Hernandez, E.
    Isaak, K. G.
    Kiss, L.
    Kuntzer, T.
    des Etangs, A. Lecavelier
    Lüftinger, T.
    Laskar, J.
    Lovis, C.
    Magrin, D.
    Malvasio, L.
    Marafatto, L.
    Michaelis, H.
    Munari, M.
    Nascimbeni, V.
    Olofsson, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    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, Gy. M.
    Thomas, N.
    Tschentscher, M.
    Udry, S.
    Viotto, V.
    Walter, I.
    Walton, N. A.
    Wildi, F.
    Wolter, D.
    The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS2020Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 643, artikkel-id A94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

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