J/A+A/707/A238ivo://CDS.VizieR/J/A+A/707/A238CDSTas K.H.Stefansson G.Fariz S.N.M.Garg E.Espinoza-Retamal J.I.,Koo E.Bruijne D.Luhn J.K.Ford E.B.Mahadevan S.Logsdon S.E.,Canas C.I.Han T.Everett M.E.Alvarado-Montes J.A.Blake C.,Cochran W.D.Dong J.Fernandes R.B.Giovinazzi M.R.Halverson S.,Kanodia S.Krolikowski D.McElwain M.Ninan J.Paredes L.A.,Robertson P.Schwab C.2026-03-17T07:16:27Z2026-03-17T08:15:52ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsk-starsphotometryvisible-astronomyWe present the discovery and confirmation of the ultra-short period (USP) planet TOI-2431 b orbiting a nearby (d~36pc) late K star (Teff=4109+/-28K) using observations from the Transiting Exoplanet Survey Satellite (TESS), precise radial velocities with the NEID and the Habitable-zone Planet Finder (HPF) spectrographs, as well as ground-based high contrast imaging from NESSI. TOI-2431 b has a period of 5 hours and 22 minutes, making it one of the shortest-period exoplanets known to date. TOI-2431 b has a radius of 1.536+/-0.033Re, and a mass of 6.2+/-1.2Me, suggesting it has a density compatible with an Earth-like composition and, due to its high irradiation, is likely a 'lava-world' with a Teq=2063+/-30K. We estimate that the current orbital period is only 30% larger than the Roche-limit orbital period, and that it has an expected orbital decay timescale of only ~31Myr. Finally, due to the brightness of the host star (V=10.9, K=7.6), TOI-2431 b has a high Emission Spectroscopy Metric of 27, making it one of the best USP systems for atmospheric phase-curve analysis.2026A&A...707A.238Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/707/A238CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/707/A238https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/707/A238http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/707/A238https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/707/A238https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/707/A238http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/707/A238GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/707/A238/rv_dataRadial velocity data from NEID and HPF (table B1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTimeBarycentric Julian Date (TDB)dtime.epochdoubleRVRadial Velocitym/sphys.veloc;pos.heliocentricfloate_RVUncertainty of Radial Velocitym/sstat.errorfloatInstInstrument name (NEID or HPF)meta.id;instrcharFCO[Y/N] Used in FCO analysismeta.codecharJ/A+A/707/A238/lc_dataTransit data from TESSrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTimeTime of Observation (BJD_TDB)dtime.epochdoubleindexedFluxNormalized fluxphot.flux;arith.ratiodoublee_FluxUncertainty of normalized fluxstat.error;phot.fluxdouble