J/A+A/699/A150ivo://CDS.VizieR/J/A+A/699/A150doi:10.26093/cds/vizier/bc-nv/lbfaCDSDeline A.Cubillos P.E.Carone L.Demory B.-O.Lendl M.Benz W.,Brandeker A.Guenther M.N.Heitzmann A.Barros S.C.C.Kreidberg L.,Bruno G.Kitzmann D.Bonfanti A.Farnir M.Persson C.M.Sousa S.G.,Wilson T.G.Ehrenreich D.Singh V.Iro N.Alibert Y.Alonso R.,Barczy T.Barrado Navascues D.Baumjohann W.Bergomi M.Billot N.,Borsato L.Broeg C.Busch M.-D.Collier Cameron A.Correia A.C.M.,Csizmadia Sz.Davies M.B.Deleuil M.Delrez L.Demangeon O.D.S.,Derekas A.Edwards B.Erikson A.Fortier A.Fossati L.Fridlund M.,Gandolfi D.Gazeas K.Gillon M.Guedel M.Hasiba J.Helling C.,Isaak K.G.Kiss L.L.Korth J.Lam K.W.F.Laskar J.,Lecavelier des Etangs A.Magrin D.Maxted P.F.L.Merin B.Mordasini C.,Nascimbeni V.Olofsson G.Ottensamer R.Pagano I.Palle E.Peter G.,Piazza D.Piotto G.Pollacco D.Queloz D.Ragazzoni R.Rando N.,Ratti F.Rauer H.Ribas I.Santos N.C.Scandariato G.Segransan D.,Simon A.E.Smith A.M.S.Stalport M.Sulis S.Szabo Gy.M.Udry S.,Van Grootel V.Venturini J.Villaver E.Walton N.A.Westerdorff K.2026-08-03T06:55:27Z2025-07-10T07:33:23ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frmultiple-starsexoplanetsphotometryvisible-astronomyUltra-hot Jupiters are gas giant exoplanets strongly irradiated by their star, which sets intense molecular dissociation leading to atmospheric chemistry dominated by ions and atoms. These conditions inhibit day-to-night heat redistribution resulting in large temperature contrast. Phase-curve observations over several passbands offer insights on the thermal structure and properties of these extreme atmospheres. We aim to perform a joint analysis of multiple observations of WASP-18 b from the visible to the mid-infrared, using unpublished data from CHEOPS, TESS and Spitzer. Our purpose is to characterise the planetary atmosphere with a consistent view over the large wavelength range covered, including JWST data. We implement a model for the planetary signal including transits, occultations, phase signal, ellipsoidal variations, Doppler boosting, and light-travel time. We fit jointly more than 250 eclipse events and derive atmospheric properties using General Circulation Models and retrieval analyses. We obtain new ephemerides with unprecedented precisions of 1 second and 1.4 millisecond on the time of inferior conjunction and orbital period, respectively. We compute a planetary radius of R_p_=1.1926+/-0.0077R_J_ with a precision of 0.65%, or 550km. Through a timing inconsistency with JWST, we discuss and confirm orbital eccentricity (e=0.00852+/-0.00091), and constrain the argument of periastron to {omega}=261.9_-1.4_^+1.3^deg. We show that the large dayside emission implies the presence of magnetic drag and super-solar metallicity. We find a steep thermally-inverted gradient in the planetary atmosphere, which is common for ultra-hot Jupiters. We detect the presence of strong CO emission lines at 4.5{mu}m from an excess of dayside brightness in the Spitzer/IRAC/Channel 2 passband. Using these models to constrain the reflected contribution in the CHEOPS passband, we derive an extremely low geometric albedo A_CHEOPS_=0.027+/-0.011. The orbital eccentricity remains a potential challenge for planetary dynamics that might require further study given the short-period massive planet and despite the young age of the system. The characterisation of the atmosphere of WASP-18 b reveals the necessity to account for magnetic friction and super-solar metallicity to explain the full picture of the dayside emission. We find the planetary dayside to be extremely unreflective, but when juxtaposing TESS and CHEOPS data, we get hints of increased scattering efficiency in the visible, likely due to Rayleigh scattering.2025A&A...699A.150Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/699/A150CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJ/707/167 : Transiting planetary system WASP-18 (Southworth+, 2009)J/A+A/567/A128 : X-ray sources in WASP-18 field (Pillitteri+, 2014)J/AcA/70/1 : WASP-18 photometric timeseries and timing datahttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/699/A150https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/699/A150http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/699/A150https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/699/A150https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/699/A150http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/699/A150GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/699/A150/cheopsrwCHEOPS raw photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTimeUTC time of observationstime.epochnullableindexedMJDMJD time of observationdtime.epochdoubleBJDBJD time of observationdtime.epochdoubleFluxRaw fluxphot.flux.density;em.optdoublee_FluxRaw flux errorstat.error;phot.fluxfloatStatusStatus flaginstr.setupintEventEvent flagmeta.code.errorintDarkDark currentphot.countdoubleBkgBackground levelinstr.backgrounddoubleContaLCContamination estimatephot.countdoublee_ContaLCContamination errorstat.errordoubleSmearLCSmearing estimatestat.fit.paramdoubleRollAngleSpacecraft roll angledeginstr.offsetdoubleLoc-XExpected PSF X locationpixinstr.det.psfintLoc-YExpected PSF Y locationpixinstr.det.psfintCent-XPSF centroid X locationpixinstr.det.psffloatCent-YPSF centroid Y locationpixinstr.det.psffloatVisitNoVisit numbermeta.id;obsintTExptimeTotal exposure timestime.duration;obs.exposureintFluxPerSecRaw fluxphot.flux.density;em.optdoublee_FluxPerSecRaw flux errorstat.errordoubleFluxNormNormalised fluxphot.flux.density;em.optdoublee_FluxNormNormalised flux errorstat.errordoubleJ/A+A/699/A150/tessrwTESS raw photometryrecnoRecord number assigned by the VizieR team. 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Should Not be used for identification.meta.recordintPhase-OrbOrbital phase (pre-proc)time.phasedoubleBJDBJD time of observation (TDB)dtime.epochdoubleFluxRawNormNormalised raw fluxphot.flux.density;em.IRdoubleFluxNormNormalised flux (pre-proc)phot.flux.density;em.IRdoublee_FluxNormNormalised flux error (pre-proc)stat.errordoubleFluxResInitResiduals (pre-proc)phot.flux.density;em.IRdoubleFluxModInitFull model (pre-proc)phot.flux.density;em.IRdoublePlanetModelInitPlanet model (pre-proc)stat.paramdoubleIRAC[1/4] IRAC channelinstr.bandpassintVisitNoVisit numbermeta.id;obsintJ/A+A/699/A150/cheopslcCHEOPS light curvese_ContaLCContamination errorstat.errordoublerecnoRecord number assigned by the VizieR team. 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