J/AJ/170/279ivo://CDS.VizieR/J/AJ/170/279CDSBeard C.Robertson P.Lubin J.Ford E.B.Mahadevan S.Stefansson G.,Wright J.T.Wolf E.Kofman V.Venkatesan V.Kopparapu R.Arendtsz R.,Holcomb R.Martinez R.A.Sallum S.Luhn J.K.Bender C.F.Blake C.H.,Cochran W.D.Delamer M.Diddams S.A.Endl M.Halverson S.Kanodia S.,Krolikowski D.M.Lin A.S.J.Logsdon S.E.McElwain M.W.Monson A.,Ninan J.P.Rajagopal J.Roy A.Schwab C.Terrien R.C.2026-08-07T12:51:57Z2026-08-07T13:36:51ZCDS support team

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

cds-question@unistra.frradial-velocityexoplanetsinfrared-astronomyspectroscopyvisible-astronomydwarf-starsm-starsWe present the discovery of GJ 251 c, a candidate super-Earth orbiting in the habitable zone (HZ) of its M dwarf host star. Using high-precision Habitable-zone Planet Finder and NEID RVs, in conjunction with archival RVs from the Keck I High Resolution Echelle Spectrometer, the Calar Alto High-resolution Search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrograph, and the Spectropolarimetre Infrarouge, we improve the measured parameters of the known planet, GJ 251 b (P_b_=14.2370days; msin(i)=3.85_-0.33_^+0.35^M_{Earth}_), and we significantly constrain the minimum mass of GJ 251 c, placing it in a plausibly terrestrial regime (P_c_=53.647+/-0.044days; msin(i_c_)=3.84+/-0.75M_{Earth}_). Using activity mitigation techniques that leverage chromatic information content, we perform a color-dependent analysis of the system and a detailed comparison of more than 50 models that describe the nature of the planets and stellar activity in the system. Due to GJ 251's proximity to Earth (5.5pc), next generation, 30m class telescopes will likely be able to image terrestrial planets in GJ 251's HZ. In fact, GJ 251 c is currently the best candidate for terrestrial, HZ planet imaging in the northern sky.2025AJ....170..279Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/170/279CatalogResearchIsServedByTAP VizieR generic servicerelated-toIII/182 : HDE Charts: positions, proper motions (Nesterov+ 1995)I/279 : Revised Luyten Half-Second Catalogue (Bakos+ 2002)I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/A+A/469/L43 : Radial velocities of Gl 581 (Udry+, 2007)J/A+A/507/487 : GJ 581 radial velocity curve (Mayor+, 2009)J/A+A/566/A130 : Rot. and variability of substellar objects (Crossfield, 2014)J/ApJ/807/45 : Potential. habitable planets orbit. M dwarfs (Dressing+, 2015)J/other/Sci/350.64 : 51 Eri b near-infrared spectrum (Macintosh+, 2015)J/AJ/152/204 : HARPS-N radial velocities of HD 179070 (Lopez-Morales+, 2016)J/AJ/153/208 : LCES HIRES/Keck radial velocity Exoplanet Survey (Butler+, 2017)J/MNRAS/472/1618 : Kepler study of starspot lifetimes (Giles+, 2017)J/ApJ/836/77 : A library of high-S/N optical spectra of FGKM stars (Yee+, 2017)J/MNRAS/474/2094 : Inferring probabilistic stellar rotat. per. (Angus+, 2018)J/A+A/613/A25 : Radial velocity for Ross 128 (Bonfils+, 2018)J/other/Nat/563.365 : Barnard's star radial velocity curve (Ribas+, 2018)J/AJ/156/102 : The TESS Input Cat. and Candidate Target List (Stassun+, 2018)J/A+A/627/A49 : Teegarden's Star RV and H{alpha} curves (Zechmeister+, 2019)J/AJ/159/100 : Flux & RVs of the dwarf G9-40 with K2 & HPF (Stefansson+, 2020)J/A+A/643/A112 : CARMENES VIS RVs of 3 M dwarfs (Stock+, 2020)J/AJ/162/61 : RV follow up of Barnard's star with HPF (Lubin+, 2021)J/ApJS/255/8 : The California Legacy Survey. I. Planet cat. (Rosenthal+, 2021)J/A+A/658/A115 : Proxima Cen ESPRESSO RV and FWHM (Faria+, 2022)J/AJ/164/97 : TESS-Keck Surv. XIII. TOI-1272 RV (MacDougall+, 2022)J/A+A/663/A48 : Two Saturn-mass planets around M dwarfs (Quirrenbach+, 2022)J/ApJ/931/L15 : Obs. of two transits of GJ 3470b with NEID (Stefansson+, 2022)J/AJ/166/62 : New HIRES radial velocity data for V1298 Tau (Blunt+, 2023)J/AJ/165/267 : O2 lvls in Near Transiting Exoplanets (Hardegree-Ullman+, 2023)J/AJ/165/34 : Habitable Zone Exopl. from NASA Exoplanet Archive (Hill+, 2023)J/A+A/670/A139 : CARMENES search for exoplanets around M dwarfs (Ribas+, 2023)J/other/Sci/382.1031 : LHS 3154 RV and activity indicators (Stefansson+, 2023)J/AJ/168/252 : SPIRou & HARPS obs. template star parameters (Artigau+, 2024)J/AJ/167/70 : TESS-Keck Surv. XVII. TOI-1136 radial velocities (Beard+, 2024)J/A+A/690/A79 : Barnard's star RV curves (Gonzalez Hernandez+, 2024)J/ApJS/272/30 : Habitable Worlds Observatory (HWO): 164 targets (Harada+, 2024)J/A+A/688/A112 : GJ 581 RVs and activity indices (von Stauffenberg+, 2024)J/A+A/693/A164 : GL725A RVs and activity indicators (Cortes-Zuleta+, 2025)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/170/279https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/170/279http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/170/279https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/170/279https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/170/279http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/170/279GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/AJ/170/279/fig6Radial velocity time series of GJ 251 (Data behind Figure 6)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJD[2450780/2460342] Barycentric Julian date at TDBdtime.epochdoubleRVel[-12.44/15.69] Radial velocity corrected for zero-point offsetm/sspect.dopplerVelocdoublee_RVel[0.18/4.74] Uncertainty in RVelm/sstat.error;spect.dopplerVelocfloatTelTelescope/Instrument used (1)instr.setupchardLW[-98.03/80.67]? Differential linewidthspect.line.widthdoublenullablee_dLW[0.2/9.33]? Uncertainty in dLWstat.error;spect.line.widthfloatnullableJ/AJ/170/279/figa3Radial velocity plot of our best Red NEID fit (Data behind Figure A3)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJD[2450780/2460342] Barycentric? Julian date at TDBdtime.epochdoubleRVel[-12.44/15.69] Radial velocity corrected for zero-point offsetm/sspect.dopplerVelocdoublee_RVel[0.36/4.74] Uncertainty in RVelm/sstat.error;spect.dopplerVelocfloatTelTelescope/Instrument used (1)instr.setupchardLW[-98.03/80.67]? Differential linewidthspect.line.widthdoublenullablee_dLW[0.2/9.33]? Uncertainty in dLWstat.error;spect.line.widthfloatnullable