J/A+A/683/A1ivo://CDS.VizieR/J/A+A/683/A1doi:10.26093/cds/vizier.36830001CDSSingh V.Scandariato G.Smith A.M.S.Cubillos P.E.Lendl M.Billot N.,Fortier A.Queloz D.Sousa S.G.Csizmadia Sz.Brandeker A.Carone L.,Wilson T.G.Akinsanmi B.Patel J.A.Krenn A.Demangeon O.D.S.Bruno G.,Pagano I.Hooton M.J.Cabrera J.Santos N.C.Alibert Y.Alonso R.,Asquier J.Barczy T.Barrado Navascues D.Barros S.C.C.Baumjohann W.,Beck M.Beck T.Benz W.Bergomi M.Bonfanti A.Bonfils X.Borsato L.,Broeg C.Charnoz S.Collier Cameron A.Davies M.B.Deleuil M.,Deline A.Delrez L.Demory B.-O.Ehrenreich D.Erikson A.Fossati L.,Fridlund M.Gandolfi D.Gillon M.Guedel M.Guenther M.N.Harre J.-V.,Heitzmann A.Helling C.Hoyer S.Isaak K.G.Kiss L.L.Lam K.W.F.,Laskar J.Lecavelier des Etangs A.Magrin D.Maxted P.F.L.Mischler H.,Mordasini C.Nascimbeni V.Olofsson G.Ottensamer R.Palle E.Peter G.,Piotto G.Pollacco D.Ragazzoni R.Rando N.Rauer H.Ribas I.,Salmon S.Segransan D.Simon A.E.Stalport M.Steinberger M.,Szabo Gy.M.Thomas N.Udry S.Ulmer B.Van Grootel V.Venturini J.,Villaver E.Walton N.A.Zingales T.2024-11-07T20:01:32Z2024-02-29T08:05:46ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsphotometryvisible-astronomyOccultations are windows of opportunity to indirectly peek into the dayside atmosphere of exoplanets. High-precision transit events provide information on the spin-orbit alignment of exoplanets around fast-rotating hosts. We aim to precisely measure the planetary radius and geometric albedo of the ultra-hot Jupiter(UHJ) KELT-20 b. We also aim to strongly constrain the KELT-20 system's spin-orbit alignment. We obtained optical high-precision transits and occultations of KELT-20 b using the CHaracterising ExOPlanet Satellite (CHEOPS). We analyzed them in conjunction with the simultaneous observations with Transiting Exoplanet Survey Satellite (TESS). We interpret the occultation measurements together with archival infrared observations to measure the planetary geometric albedo and dayside temperatures. We further use the host star's gravity-darkened nature to measure the system's obliquity. We present time-averaged precise occultation depth of 82+/-6ppm measured with seven CHEOPS visits and 131^+8^_-7_ ppm from the analysis of all available TESS photometry. Using these measurements, we precisely constrain the geometric albedo of KELT-20 b to 0.26+/-0.04 and the brightness temperature of the dayside hemisphere to 2566^+77^_-80_K. Assuming Lambertian scattering law, we constrain the Bond albedo to 0.36^+0.04^_-0.05_ along with a minimal heat transfer to the nightside (<=0.14^+0.13^_-0.10_). Furthermore, using five transit observations we provide stricter constraints of 3.9+/-1.1-degrees on the sky-projected obliquity of the system. Conclusions. The aligned orbit of KELT-20 b is in contrast to previous CHEOPS studies that have found strongly inclined orbits for planets orbiting other A-type stars. KELT-20 b's comparably high planetary geometric albedo corroborates a known trend of strongly irradiated planets being more reflective. Finally, we tentatively detect signs of temporal variability in the occultation depths, which might indicate variable cloud cover advecting onto the planetary dayside.2024A&A...683A...1Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/683/A1CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/612/A57 : MASCARA-2b (HD185603) light curves and spectra (Talens+, 2018)J/A+A/616/A151 : MASCARA-2b NaI + Ha absorption lines (Casasayas-Barris+, 2018)J/A+A/628/A9 : MASCARA-2b transmission spectra (Casasayas-Barris+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/683/A1https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/683/A1http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/683/A1https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/683/A1https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/683/A1http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/683/A1GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/683/A1/tablec1PIPE extracted CHEOPS light curve of KELT-20MJDMJD time of observationdtime.epochdoubleBJDBJD time of observationdtime.epochdoubleFluxFlux countsctphot.flux.density;em.optdoublee_FluxError flux countsctstat.error;phot.fluxdoubleBGBackground Fluxctinstr.backgrounddoubleRollRoll angledeginstr.offsetdoubleCentxCentroid xpos.cartesian.x;instr.detdoubleCentyCentroid ypos.cartesian.y;instr.detdoubleFlag[0/25] Flag to designate bad datameta.code.errorfloatTThermFront2 thermistor readout (Telescope temperature)Kphys.temperaturedoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJ/A+A/683/A1/lc_detLight curve detrended (corrected version, 19-Aug-2024)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBJD time of observationdtime.epochdoubleFluxRelative fluxphot.flux;arith.ratiodoublee_FluxRelative flux errorstat.error;phot.fluxdouble