J/A+A/694/A143ivo://CDS.VizieR/J/A+A/694/A143doi:10.26093/cds/vizier.36940143CDSThomas L.Hebrard G.Kellermann H.Korth J.Heidari N.Forveille T.,Sousa S.G.Schoeller L.Riffeser A.Goessl C.Serrano Bell J.,Kiefer F.Hara N.Grupp F.Ehrhardt J.Murgas F.Collins K.A.,Bieryla A.Parviainen H.Belinski A.A.Esparza-Borges E.Ciardi D.R.,Clark C.A.Fukui A.Gilbert E.A.Hopp U.Ikuta K.Jenkins J.M.,Latham D.W.Narita N.Nielsen L.D.Quinn S.N.Palle E.Pippert J.-N.,Polanski A.S.Ries C.Schmidt M.Schwarz R.P.Seager S.Strakhov I.A.,Striegel S.van Eyken J.C.Watanabe N.Watkins C.N.Winn J.N.,Ziegler C.Zoeller R.2025-05-21T20:01:23Z2025-02-07T12:14:53ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsradial-velocityvisible-astronomyWe report the discovery and characterization of two sub-Saturns from the Transiting Exoplanet Survey Satellite (TESS) using high-resolution spectroscopic observations from the MaHPS spectrograph at the Wendelstein Observatory and the SOPHIE spectrograph at the Haute-Provence Observatory. Combining photometry from TESS, KeplerCam, LCOGT, and MuSCAT2 with the radial velocity measurements from MaHPS and SOPHIE we measure precise radii and masses for both planets. TOI-5108 b is a sub-Saturn with a radius of 6.6+/-0.1R_{Earth}_ and a mass of 32+/-5M_{Earth}_ TOI-5786 b is similar to Saturn with a radius of 8.63+/-0.12R_{Earth}_ and a mass of 72+/-8M_{Earth}_. Both planets are close to their host stars with periods of 6.75 days and 12.78 days respectively. This puts TOI-5108 b just inside the bounds of the Neptune desert while TOI-5786 b is right above the upper edge. We estimate hydrogen-helium envelope mass fractions of 38% for TOI-5108 b and 74% for TOI-5786 b. However, using a model for the interior structure that includes tidal effects the envelope fraction of TOI-5108 b could be much lower (~20$) depending on the obliquity. We estimate mass-loss rates between 1.0x10^9^g/s and 9.8x10^9^g/s for TOI-5108 b and between 3.6x10^8^g/s and 3.5x10^9^g/s for TOI-5786 b. Given their masses, this means that both planets are stable against photoevaporation. Furthermore, at these mass-loss rates, there is likely no detectable signal in the metastable helium triplet with the James Webb Space Telescope. We also detect a transit signal for a second planet candidate around TOI-5786 with a period of 6.998 days and a radius of 3.90+/-0.16R_{Earth}_ Using our RV data and photodynamical modeling, we are able to provide a 3-{sigma} upper limit of 26.5M_{Earth}_ for the mass of the potential inner companion to TOI-5786 b.2025A&A...694A.143Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/694/A143CatalogResearchIsServedByTAP VizieR generic servicerelated-toIV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/694/A143https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/694/A143http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/694/A143https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/694/A143https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/694/A143http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/694/A143GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/694/A143/toi5108TOI-5108 RV data (table 8)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTimeTime of observation in BJDdtime.epochdoubleRVRadial velocity (relative for MAHPS observations)m/sphys.veloc;pos.heliocentricdoublee_RVError of the radial velocitym/sstat.errordoubleInstInstrument used for the observation (MAHPS or SOPHIE)instr.setupcharJ/A+A/694/A143/toi5786TOI-5786 RV data (table 9)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTimeTime of observation in BJDdtime.epochdoubleRVRadial velocity (relative for MAHPS observations)m/sphys.veloc;pos.heliocentricdoublee_RVError of the radial velocitym/sstat.errordoubleInstInstrument used for the observation (MAHPS or SOPHIE)instr.setupchar