J/A+A/696/A28ivo://CDS.VizieR/J/A+A/696/A28doi:10.26093/cds/vizier.36960028CDSEgger J.A.Kubyshkina D.Alibert Y.Osborn H.P.Bonfanti A.,Wilson T.G.Brandeker A.Guenther M.N.Lendl M.Kitzmann D.,Fossati L.Mordasini C.Sousa S.G.Adibekyan V.Fridlund M.,Pezzotti C.Gandolfi D.Ulmer-Moll S.Alonso R.Barczy T.,Barrado Navascues D.Barros S.C.Baumjohann W.Benz W.Billot N.,Borsato L.Broeg C.Collier Cameron A.Correia A.C.M.Csizmadia Sz.,Cubillos P.E.Davies M.B.Deleuil M.Deline A.Demangeon O.D.S.,Demory B.-O.Derekas A.Edwards B.Ehrenreich D.Erikson A.Fortier A.,Gazeas K.Gillon M.Guedel M.Heitzmann A.Helling C.Isaak K.G.,Kiss L.Korth J.Lam K.W.F.Laskar J.Lecavelier des Etangs A.,Luntzer A.Luque R.Magrin D.Maxted P.F.L.Merin B.Munari M.,Nascimbeni V.Olofsson G.Ottensamer R.Pagano I.Palle E.Peter G.,Piazza D.Piotto G.Pollacco D.Queloz D.Ragazzoni R.Rando N.,Rauer H.Ribas I.Santos N.C.Scandariato G.Segransan D.Simon A.E.,Smith A.M.S.Southworth R.Stalport M.Sulis S.Szabo M.Gy.Udry S.,Van Grootel V.Venturini J.Villaver E.Walton N.A.Wolf S.Wolter D.2025-06-02T20:01:20Z2025-04-01T12:35:37ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsphotometryvisible-astronomyStudying the composition of exoplanets is one of the most promising approaches to observationally constrain planet formation and evolution processes. However, this endeavour is complicated for small exoplanets by the fact that a wide range of compositions is compatible with their observed bulk properties. To overcome this issue, we identify triangular regions in the mass-radius space where part of this intrinsic degeneracy is lifted for close-in planets, since low-mass H/He envelopes would not be stable due to high-energy stellar irradiation. Planets in these Hot Water World triangles need to contain at least some heavier volatiles and are therefore interesting targets for atmospheric follow-up observations. We perform a demographic study to show that only few well-characterised planets in these regions are currently known and introduce our CHEOPS GTO programme aimed at identifying more of these potential hot water worlds. Here, we present CHEOPS observations for the first two targets of our programme, TOI-238 b and TOI-1685 b. Combined with TESS photometry and published RVs, we use the precise radii and masses of both planets to study their location relative to the corresponding Hot Water World triangles, perform an interior structure analysis and study the possible lifetimes of H/He and water-dominated atmospheres under these conditions. We find that TOI-238 b lies, at the 1sigma level, inside the corresponding triangle. While a pure H/He atmosphere would have evaporated after 0.4-1.3Myr, it is likely that a water-dominated atmosphere would have survived until the current age of the system, which makes TOI-238 b a promising candidate for a hot water world. Conversely, TOI-1685 b lies below the mass-radius model for a pure silicate planet, meaning that even though a water-dominated atmosphere would be compatible both with our internal structure and evaporation analysis, we cannot rule out the planet to be a bare core.2025A&A...696A..28Ehttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/696/A28CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/696/A28https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/696/A28http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/696/A28https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/696/A28https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/696/A28http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/696/A28GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/696/A28/ctoi238CHEOPS photometry and model fits for TOI-238recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCcmodel+2sigPlanet c model (+2sig) (cheops_cmodel_+2sig)stat.paramfloatIndexIndex (index)meta.idintTimeBJD time (time)dtime.epochdoubleFluxNormalised flux (in ppt unit) (flux)phot.flux;arith.ratiodoublee_FluxNormalised flux error (in ppt unit) (flux_err)stat.error;phot.fluxdoublephiRoll angle (phi)deginstr.offsetdoublebgBackground (bg)instr.backgrounddoubleCentroidXPSF X centroid (centroidx)pixpos.cartesian.x;instr.detdoubleCentroidYPSF Y centroid (centroidy)pixinstr.det.psfdoubledeltaTTemperature change (deltaT)phys.temperaturedoubleXoffPSF X centroid offset (xoff)pixpos.cartesian.x;instr.detdoubleYoffPSF Y centroid offset (yoff)pixpos.cartesian.y;instr.detdoublenphimodelIndex for rollangle model (n_phi_model)meta.idintCpredsp-2sigSpline detrend model (-2sig) (cheops_pred_spline_-2sig)stat.paramdoubleCpredsp-1sigSpline detrend model (-1sig) (cheops_pred_spline_-1sig)stat.paramdoubleCpredspmedSpline detrend model (median) (cheops_pred_spline_med)stat.paramdoubleCpredsp+1sigSpline detrend model (+1sig) (cheops_pred_spline_+1sig)stat.paramdoubleCpredsp+2sigSpline detrend model (+2sig) (cheops_pred_spline_+2sig)stat.paramdoubleCldetre-2sigDecorrelation detrend model (-2sig) (cheops_lindetrend_-2sig)stat.paramdoubleCalldet-2sigSum of detrend models (-2sig) (cheops_alldetrend_-2sig)stat.paramdoubleCbmodel-2sigPlanet b model (-2sig) (cheops_bmodel_-2sig)stat.paramdoubleCcmodel-2sigPlanet c model (-2sig) (cheops_cmodel_-2sig)stat.paramfloatCallplmodel-2sigSum of planet models (-2sig) (cheops_allplmodel_-2sig)stat.paramdoubleCldetre-1sigDecorrelation detrend model (-1sig) (cheops_lindetrend_-1sig)stat.paramdoubleCalldet-1sigSum of detrend models (-1sig) (cheops_alldetrend_-1sig)stat.paramdoubleCbmodel-1sigPlanet b model (-1sig) (cheops_bmodel_-1sig)stat.paramdoubleCcmodel-1sigPlanet c model (-1sig) (cheops_cmodel_-1sig)stat.paramfloatCallplmodel-1sigSum of planet models (-1sig) (cheops_allplmodel_-1sig)stat.paramdoubleCldetremedDecorrelation detrend model (median) (cheops_lindetrend_med)stat.paramdoubleCalldetmedSum of detrend models (median) (cheops_alldetrend_med)stat.paramdoubleCbmodelmedPlanet b model (median) (cheops_bmodel_med)stat.paramdoubleCcmodelmedPlanet c model (median) (cheops_cmodel_med)stat.paramfloatCallplmodelmedSum of planet models (median) (cheops_allplmodel_med)stat.paramdoubleCldetre+1sigDecorrelation detrend model (+1sig) (cheops_lindetrend_+1sig)stat.paramdoubleCalldet+1sigSum of detrend models (+1sig) (cheops_alldetrend_+1sig)stat.paramdoubleCbmodel+1sigPlanet b model (+1sig) (cheops_bmodel_+1sig)stat.paramdoubleCcmodel+1sigPlanet c model (+1sig) (cheops_cmodel_+1sig)stat.paramfloatCallplmodel+1sigSum of planet models (+1sig) (cheops_allplmodel_+1sig)stat.paramdoubleCldetre+2sigDecorrelation detrend model (+2sig) (cheops_lindetrend_+2sig)stat.paramdoubleCalldet+2sigSum of detrend models (+2sig) (cheops_alldetrend_+2sig)stat.paramdoubleCbmodel+2sigPlanet b model (+2sig) (cheops_bmodel_+2sig)stat.paramdoubleCallplmodel+2sigSum of planet models (+2sig) (cheops_allplmodel_+2sig)stat.paramdoubleFilekeyCHEOPS file key (filekey)meta.id;meta.filecharJ/A+A/696/A28/ttoi238TESS photometry and model fits for TOI-238recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIndexIndex (index)meta.idintTimeBJD time (time)dtime.epochdoubleindexedFluxNormalised flux (in ppt unit) (flux)phot.flux;arith.ratiodoublee_FluxNormalised flux error (in ppt unit) (flux_err)stat.error;phot.fluxdoubleMaskBoolean flux mask (mask)meta.codecharNearTransAll planet near-transit mask (near_trans)meta.codecharinTransbIn-transit mask of planet b (in_trans_b)meta.codecharinTranscIn-transit mask of planet c (in_trans_c)meta.codecharinTransallAll planet in-transit mask (in_trans_all)meta.codecharsplineTransit-masked flux bspline (spline)meta.codedoubleFluxflatSpline-flattened flux (flux_flat)phot.flux;meta.modelleddoubleTgpmodelmedGP detrend model (median) (tess_gpmodel_med)stat.paramdoubleTbmodel-2sigPlanet b model (-2sig) (tess_bmodel_-2sig)stat.paramdoubleTcmodel-2sigPlanet c model (-2sig) (tess_cmodel_-2sig)stat.paramdoubleTallplmodel-2sigSum of planet models (-2sig) (tess_allplmodel_-2sig)stat.paramdoubleTbmodel-1sigPlanet b model (-1sig) (tess_bmodel_-1sig)stat.paramdoubleTcmodel-1sigPlanet c model (-1sig) (tess_cmodel_-1sig)stat.paramdoubleTallplmodel-1sigSum of planet models (-1sig) (tess_allplmodel_-1sig)stat.paramdoubleTbmodelmedPlanet b model (median) (tess_bmodel_med)stat.paramdoubleTcmodelmedPlanet c model (median) (tess_cmodel_med)stat.paramdoubleTallplmodelmedSum of planet models (median) (tess_allplmodel_med)stat.paramdoubleTbmodel+1sigPlanet b model (+1sig) (tess_bmodel_+1sig)stat.paramdoubleTcmodel+1sigPlanet c model (+1sig) (tess_cmodel_+1sig)stat.paramdoubleTallplmodel+1sigSum of planet models (+1sig) (tess_allplmodel_+1sig)stat.paramdoubleTbmodel+2sigPlanet b model (+2sig) (tess_bmodel_+2sig)stat.paramdoubleTcmodel+2sigPlanet c model (+2sig) (tess_cmodel_+2sig)stat.paramdoubleTallplmodel+2sigSum of planet models (+2sig) (tess_allplmodel_+2sig)stat.paramdoubleJ/A+A/696/A28/ctoi1685CHEOPS photometry and model fits for TOI-238Cpredsp-2sigSpline detrend model (-2sig) (cheops_pred_spline_-2sig)stat.paramdoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIndexIndex (index)meta.idintTimeBJD time (time)dtime.epochdoubleFluxNormalised flux (in ppt unit) (flux)phot.flux;arith.ratiodoublee_FluxNormalised flux error (in ppt unit) (flux_err)stat.error;phot.fluxdoublephiRoll angle (phi)deginstr.offsetdoublebgBackground (bg)instr.backgrounddoubleCentroidXPSF X centroid (centroidx)pixpos.cartesian.x;instr.detdoubleCentroidYPSF Y centroid (centroidy)pixinstr.det.psfdoubledeltaTTemperature change (deltaT)mKphys.temperaturedoubleXoffPSF X centroid offset (xoff)pixpos.cartesian.x;instr.detdoubleYoffPSF Y centroid offset (yoff)pixpos.cartesian.y;instr.detdoubleFilekeyCHEOPS file key (filekey)meta.id;meta.filecharnphimodelIndex for rollangle model (n_phi_model)meta.idintCpredsp-1sigSpline detrend model (-1sig) (cheops_pred_spline_-1sig)stat.paramdoubleCpreds-pmedSpline detrend model (median) (cheops_pred_spline_med)stat.paramdoubleCpredsp+1sigSpline detrend model (+1sig) (cheops_pred_spline_+1sig)stat.paramdoubleCpredsp+2sigSpline detrend model (+2sig) (cheops_pred_spline_+2sig)stat.paramdoubleCldetre-2sigDecorrelation detrend model (-2sig) (cheops_lindetrend_-2sig)stat.paramdoubleCalldet-2sigSum of detrend models (-2sig) (cheops_alldetrend_-2sig)stat.paramdoubleCbmodel-2sigPlanet b model (-2sig) (cheops_bmodel_-2sig)stat.paramdoubleCallplmodel-2sigSum of planet models (-2sig) (cheops_allplmodel_-2sig)stat.paramdoubleCldetre-1sigDecorrelation detrend model (-1sig) (cheops_lindetrend_-1sig)stat.paramdoubleCalldet-1sigSum of detrend models (-1sig) (cheops_alldetrend_-1sig)stat.paramdoubleCbmodel-1sigPlanet b model (-1sig) (cheops_bmodel_-1sig)stat.paramdoubleCallplmodel-1sigSum of planet models (-1sig) (cheops_allplmodel_-1sig)stat.paramdoubleCldetre-medDecorrelation detrend model (median) (cheops_lindetrend_med)stat.paramdoubleCalldet-medSum of detrend models (median) (cheops_alldetrend_med)stat.paramdoubleCbmodel-medPlanet b model (median) (cheops_bmodel_med)stat.paramdoubleCallplmodel-medSum of planet models (median) (cheops_allplmodel_med)stat.paramdoubleCldetre+1sigDecorrelation detrend model (+1sig) (cheops_lindetrend_+1sig)stat.paramdoubleCalldet+1sigSum of detrend models (+1sig) (cheops_alldetrend_+1sig)stat.paramdoubleCbmodel+1sigPlanet b model (+1sig) (cheops_bmodel_+1sig)stat.paramdoubleCallplmodel+1sigSum of planet models (+1sig) (cheops_allplmodel_+1sig)stat.paramdoubleCldetre+2sigDecorrelation detrend model (+2sig) (cheops_lindetrend_+2sig)stat.paramdoubleCalldet+2sigSum of detrend models (+2sig) (cheops_alldetrend_+2sig)stat.paramdoubleCbmodel+2sigPlanet b model (+2sig) (cheops_bmodel_+2sig)stat.paramdoubleCallplmodel+2sigSum of planet models (+2sig) (cheops_allplmodel_+2sig)stat.paramdoubleJ/A+A/696/A28/ttoi1685TESS photometry and model fits for TOI-238recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIndexIndex (index)meta.idintFluxNormalised flux (in ppt unit) (flux)phot.flux;arith.ratiodoublee_FluxNormalised flux error (in ppt unit) (flux_err)stat.error;phot.fluxdoubleNearTransAll planet near-transit mask (near_trans)meta.codecharinTransbIn-transit mask of planet b (in_trans_b)meta.codecharinTransallAll planet in-transit mask (in_trans_all)meta.codecharsplineTransit-masked flux bspline (spline)meta.codedoubleFluxflatSpline-flattened flux (flux_flat)phot.flux;meta.modelleddoubleTgpmodelmedGP detrend model (tess_gpmodel_med)stat.paramdoubleTbmodel-2sigPlanet b model (-2sig) (tess_bmodel_-2sig)stat.paramdoubleTallplmodel-2sigSum of planet models (-2sig) (tess_allplmodel_-2sig)stat.paramdoubleTbmodel-1sigPlanet b model (-1sig) (tess_bmodel_-1sig)stat.paramdoubleTallplmodel-1sigSum of planet models (-1sig) (tess_allplmodel_-1sig)stat.paramdoubleTbmodel-medPlanet b model (median) (tess_bmodel_med)stat.paramdoubleTallplmodel-medSum of planet models (median) (tess_allplmodel_med)stat.paramdoubleTbmodel-+1sigPlanet b model (+1sig) (tess_bmodel_+1sig)stat.paramdoubleTallplmodel-+1sigSum of planet models (+1sig) (tess_allplmodel_+1sig)stat.paramdoubleTbmodel-+2sigPlanet b model (+2sig) (tess_bmodel_+2sig)stat.paramdoubleTallplmodel-+2sigSum of planet models (+2sig) (tess_allplmodel_+2sig)stat.paramdoubleTimeBJD time (time)dtime.epochdoubleindexedMaskBoolean flux mask (mask)meta.codechar