J/A+A/659/L4ivo://CDS.VizieR/J/A+A/659/L4doi:10.26093/cds/vizier.36599004CDSBrandeker A.Heng K.Lendl M.Patel J.A.Morris B.M.Broeg C.,Guterman P.Beck M.Maxted P.F.L.Demangeon O.Delrez L.Demory B.-O.,Kitzmann D.Santos N.C.Singh V.Alibert Y.Alonso R.Anglada G.,Barczy T.Barrado y Navascues D.Barros S.C.C.Baumjohann W.Beck T.,Benz W.Billot N.Bonfils X.Bruno G.Cabrera J.Charnoz S.,Collier Cameron A.Corral van Damme C.Csizmadia Sz.Davies M.B.,Deleuil M.Deline A.Ehrenreich D.Erikson A.Farinato J.Fortier A.,Fossati L.Fridlund M.Gandolfi D.Gillon M.Guedel M.Hoyer S.,Isaak K.G.Kiss L.Laskar J.Lecavelier des Etangs A.Lovis C.,Luntzer A.Magrin D.Nascimbeni V.Olofsson G.Ottensamer R.Pagano I.,Palle E.Peter G.Piotto G.Pollacco D.Queloz D.Ragazzoni R.,Rando N.Rauer H.Ribas I.Scandariato G.Segransan D.Simon A.E.,Smith A.M.S.Sousa S.G.Steller M.Szabo G.M.Thomas N.Udry S.,Van Grootel V.Walton N.Wolter D.2022-09-05T14:25:55Z2022-03-02T08:52:08ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsphotometryWe report the detection of the secondary eclipse of the hot Jupiter HD 209458 b in optical/visible light using the CHEOPS space telescope. Our measurement of 20.4^+3.2^_3.3_ parts per million (ppm) translates into a geometric albedo of Ag=0.096+/-0.016. The previously estimated dayside temperature of about 1500K implies that our geometric albedo measurement consists predominantly of reflected starlight and is largely uncontaminated by thermal emission. This makes the present result one of the most robust measurements of Ag for any exoplanet, critical for understanding the atmosphere. Our calculations of the bandpass-integrated geometric albedo demonstrate that the measured value of Ag is consistent with a cloud-free atmosphere, where starlight is reflected via Rayleigh scattering by hydrogen molecules, with water and sodium abundances consistent with stellar metallicity. We predict that the bandpass-integrated TESS geometric albedo is too faint to detect and that a phase curve of HD 209458 b observed by CHEOPS would have a distinct shape associated with Rayleigh scattering if the atmosphere is indeed cloud-free.2022A&A...659L...4Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/659/L4CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/659/L4https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/659/L4http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/659/L4https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/659/L4https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/659/L4http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/659/L4GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/659/L4/tableRaw photometric time series with auxiliary detrending vectorsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJD[2459422.96/2459479.83] Julian date of observationdtime.epochdoubleindexedNFlux[0.99/1.01] Normalised raw fluxphot.fluxdoublee_NFlux[0.0/0.01] 1-sigma uncertainty in NFluXstat.errordoubleRollAngle[0.03/360.0] Roll angledeginstr.offsetdoubleCenX[27.44/30.98] x-centroid positionpos.cartesian.x;instr.detdoubleCenY[29.42/32.65] y-centroid positionpos.cartesian.y;instr.detdoubleBG[0.0/0.01] Backgroundinstr.backgrounddoubleJ/A+A/659/L4/table1Detrended and phase-folded light curverecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTime[-0.28/0.24] Time from eclipse centerdtime.epochdoubleindexedNFlux[0.99/1.01] Normalised flux, after detrending and correcting for systematics and other trendsphot.fluxdoublee_NFlux[0.0/0.01] 1-sigma uncertainty in NFluxstat.errordouble