J/MNRAS/548/G520ivo://CDS.VizieR/J/MNRAS/548/G520CDSPalethorpe L.Mortier A.Egger J.A.Rice K.Wilson T.G.Vanderburg A.,Bonomo A.S.Boschin W.Cameron A.C.Eschen Y.N.E.Harutyunyan A.,Malavolta L.Fiorenzano A.F.M.Sozzetti A.Stalport M.Van Eylen V.,Watson C.A.2026-06-23T06:26:39Z2026-06-23T07:20:10ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsradial-velocityvisible-astronomyAccurate mass and radius measurements of small transiting exoplanets are essential for probing their compositions, formation histories, and potential habitability. We present a uniform analysis of six planetary systems (each hosting at least one small transiting planet): K2-79, K2-106, K2-111, K2-222, K2-263, and TOI-1634. Our study combines new CHEOPS transit observations with archival photometry from K2, TESS, and ground-based facilities, alongside new and archival radial velocity data from HARPS-N, HIRES, ESPRESSO, and others. For each system, we perform joint transit and RV modelling, achieving typical precisions better than 15 per cent and 5 per cent for mass and radius, respectively, and thus enabling precise bulk density determinations. These reveal a range of compositions, including rocky planets near the radius valley (e.g. K2-106 b, TOI-1634 b), intermediate-density planets requiring steam-rich or mixed volatile envelopes (e.g. K2-111 b, K2-263 b), and low-density regimes, consistent with gas dwarfs or water-worlds (e.g. K2-79 b, K2-222 b). Several systems show evidence of additional companions detectable via RVs but not seen in transit. The results highlight the value of coordinated CHEOPS and HARPS-N observations in delivering some of the most precise bulk densities for small planets to date and support the preparation for future atmospheric characterization missions.2026MNRAS.548g.520Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/548/G520CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/548/G520https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/548/G520http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/548/G520https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/548/G520https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/548/G520http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/548/G520GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/MNRAS/548/G520/tablea1HARPS-N RV DRS reduced data for K2-79recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Daydtime.epochdoubleRVRadial Velocity (relative radial velocity for table 6)m/sphys.veloc;pos.heliocentricdoublee_RVError in radial velocitym/sstat.errordoubleJ/MNRAS/548/G520/tablea2HARPS-N RV DRS reduced data for K2-106recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Daydtime.epochdoubleRVRadial Velocity (relative radial velocity for table 6)m/sphys.veloc;pos.heliocentricdoublee_RVError in radial velocitym/sstat.errordoubleJ/MNRAS/548/G520/tablea3HARPS-N RV DRS reduced data for K2-111recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Daydtime.epochdoubleRVRadial Velocity (relative radial velocity for table 6)m/sphys.veloc;pos.heliocentricdoublee_RVError in radial velocitym/sstat.errordoubleJ/MNRAS/548/G520/tablea4HARPS-N RV DRS reduced data for K2-222recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Daydtime.epochdoubleRVRadial Velocity (relative radial velocity for table 6)m/sphys.veloc;pos.heliocentricdoublee_RVError in radial velocitym/sstat.errordoubleJ/MNRAS/548/G520/tablea5HARPS-N RV DRS reduced data for K2-263recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Daydtime.epochdoubleRVRadial Velocity (relative radial velocity for table 6)m/sphys.veloc;pos.heliocentricdoublee_RVError in radial velocitym/sstat.errordoubleJ/MNRAS/548/G520/tablea6HARPS-N RV TERRA reduced data for TOI-1634recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Daydtime.epochdoubleRVRadial Velocity (relative radial velocity for table 6)m/sphys.veloc;pos.heliocentricdoublee_RVError in radial velocitym/sstat.errordouble