J/A+A/707/A197ivo://CDS.VizieR/J/A+A/707/A197CDSBonomo A.S.Naponiello L.Sozzetti A.Benatti S.Carleo I.Biazzo K.,Cubillos P.E.Damasso M.Di Maio C.Dorn C.Hara N.Polychroni D.,Steinmeyer M.-L.Collins K.A.Desidera S.Dumusque X.Lanza A.F.,Safonov B.S.Stockdale C.Turrini D.Ziegler C.Affer L.D'Arpa M.,Fardella V.Harutyunyan A.Lorenzi V.Malavolta L.Mancini L.,Mantovan G.Micela G.Murgas F.Nardiello D.Pagano I.Palle E.,Pedani M.Pinamonti M.Rainer M.Scandariato G.Spinelli R.,Zingales T.2026-04-02T06:28:33Z2026-03-10T10:32:13ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsspectroscopyvisible-astronomyradial-velocitySub-Neptunes with planetary radii of R_p_=~2-4 R_{Earth}_ are the most common planets around solar-type stars in short-period (P<100d) orbits. It is still unclear, however, what their most likely composition is, that is whether they are predominantly gas dwarfs or water worlds. The sub-Neptunes orbiting bright host stars are very valuable because they are suitable for atmospheric characterization, which can break the well-known degeneracy in planet composition from the planet bulk density, when combined with a precise and accurate mass measurement. Here we report on the characterization of the sub-Neptune TOI-5789 c, which transits in front of the bright (V=7.3mag and K_s_=5.35mag) and magnetically inactive K1V dwarf HIP 99452 every 12.93 days, thanks to TESS photometry and 141 high-precision radial velocities obtained with the HARPS-N spectrograph. We find that its radius, mass, and bulk density are R_c_=2.86^+0.18^_-0.15_R_{Earth}_, M_c_=5.00+/-0.50M_{Earth}_, and {rho}_c_=1.16+/-0.23gcm^-3^, and we show that TOI-5789c is a promising target for atmospheric characterization with both JWST and, in the future, Ariel. By analyzing the HARPS-N radial velocities with different tools, we also detect three additional non-transiting planets, namely TOI-5789b, d, and e, with orbital periods and minimum masses of P_b_=2.76 d, M_b_sini=2.12+/-0.28, P_d_=29.6d, M_d_sini=4.29+/-0.68M_{Earth}_, and P_e_=63.0d, M_e_sini=11.61+/-0.97M_{Earth}_. TOI-5789 is a mutually inclined system as the difference between the orbital inclinations of planets b and c must be higher than ~4deg. Nevertheless, from sensitivity studies based on both the HARPS-N and archival HIRES radial-velocity measurements, we can exclude that these relatively high mutual inclinations are due to the perturbation by an outer gaseous giant planet.2026A&A...707A.197Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/707/A197CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/693/A7 : BD+00 444 (TOI-2443) RV curves (Naponiello+, 2025)J/A+A/677/A33 : 38 Kepler and K2 systems RVs (Bonomo+, 2023)J/A+A/657/A7 : Stellar and substellar companions from Gaia EDR3J/A+A/573/A101 : Generalised Lomb-Scargle periodogram codeJ/A+A/562/A71 : Chemical abundances of solar neighbourhood dwarfsJ/A+A/388/632 : Radial-velocity of HD 108147 and HD 168746 (Pepe+, 2002)J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS)J/ApJ/790/146 : Planets in Kepler's multi-transiting systemsJ/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+,2014)J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)J/MNRAS/472/1618 : Kepler study of starspot lifetimes (Giles+, 2017)J/MNRAS/459/3890 : ExoMol line lists for SO2 (Underwood+, 2016)J/ApJS/254/39 : Exoplanet candidates from TESS first 2yr obsJ/ApJS/254/42 : Hipparcos-Gaia (EDR3) Catalog of AccelerationsJ/AJ/159/19 : SOAR TESS survey. I. (Ziegler+, 2020)J/AJ/157/52 : Radial velocity observations in super-Earth systemsJ/AJ/156/102 : The TESS Input Catalog and Candidate Target ListJ/AJ/154/109 : California-Kepler Survey (CKS). III. Planet radiiJ/AJ/147/20 : Spectroscopy of 447 nearby M dwarfs (Newton+, 2014)J/AZh/97/733 : Binary Star Pop. with Common Proper MotionIV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)II/336 : AAVSO Photometric All Sky Survey (APASS) DR9II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)I/348 : Orbital parameters in Milky-Way-like potentialsI/259 : The Tycho-2 Catalogue (Hog+ 2000)J/other/ExA/51.109 : Transit KELT-11b observed by CHEOPS (Benz+, 2021)J/other/Sci/377.1211 : RV and LC of 8 M dwarf stars with planets (Luque+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/707/A197https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/707/A197http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/707/A197https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/707/A197https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/707/A197http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/707/A197GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/707/A197/tablea1HARPS-N measurements of radial velocity and activity indicators of TOI-5789recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDEpochs of measurements TDB (BJD-2450000)dtime.epochdoubleRVRadial velocitym/sphys.veloc;pos.heliocentricdoublee_RV1-sigma uncertainty of the radial velocitym/sstat.errorfloatFWHMFull with at half maximum of the cross correlation functionm/sspect.line.widthfloate_FWHM1-sigma uncertainty of the full with at half maximumm/sstat.error;phys.angSizefloatBISBisector span of the cross correlation functionm/sphys.velocfloate_BIS1-sigma uncertainty of the bisector spanm/sstat.errorfloatCContrast of the cross correlation function%phot.flux;arith.ratiofloate_C1-sigma uncertainty of the contrast%stat.errorfloatSMWCaII H&K Mount Wilson S-indexphot.flux;arith.ratiofloate_SMW1-sigma uncertainty of the S-indexstat.errorfloatlog(R'HK)Logarithm of the R'_HK_ activity indexphot.flux;arith.ratiofloate_log(R'HK)1-sigma uncertainty of the logarithm of the R'_HK_ activity indexstat.errorfloat