J/AJ/170/335ivo://CDS.VizieR/J/AJ/170/335CDSBrady M.Bean J.L.Basant R.Brown N.Das T.Nixon M.C.Luque R.,Piaulet-Ghorayeb C.Radica M.Seifahrt A.Sturmer J.Zhao L.2026-09-02T13:00:29Z2026-09-02T13:51:07ZCDS support team

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

cds-question@unistra.frexoplanetsradial-velocityvisible-astronomyspectroscopym-starsdwarf-starsWhile JWST has provided us with the opportunity to probe the atmospheres of potentially habitable planets, observations of the TRAPPIST-1 system have shown us that active stars severely complicate efforts at studying their planets. GJ 12 b is a newly discovered temperate (T_eq_~300K), Earth-sized (R_p_=0.96+/-0.05R_{Earth}_) planet orbiting an inactive M dwarf that might be a good alternate to the TRAPPIST-1 planets for atmospheric characterization. In this paper, we use MAROON-X radial velocities to measure a mass of 0.70+/-0.10M_{Earth}_ for GJ 12 b. We also recover a planetary eccentricity of 0.24, but there is no strong evidence that the planet has an eccentric orbit. GJ 12 b's mass results in a planetary density comparable to or less dense than that of Earth, possibly indicating the presence of water or a low bulk iron mass fraction. With its low mass, GJ 12 b is likely within reach of JWST transmission spectroscopy observations, making it an excellent target for determining the location of the cosmic shoreline. Its low mass may mean that the planet could have trouble retaining its primary atmosphere during the star's active pre-main-sequence phase. However, if it has a heightened eccentricity, it may be able to sustain a secondary atmosphere through tidally induced volcanism.2025AJ....170..335Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/170/335CatalogResearchIsServedByTAP VizieR generic servicerelated-toIII/150A : Perkins Revised MK Types for the Cooler Stars (Keenan+ 1989)II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)I/350 : Gaia EDR3 (Gaia Collaboration, 2020)J/ApJ/694/1085 : Radii of exoplanet host stars (van Belle+, 2009)J/AJ/147/20 : Spectroscopy of 447 nearby M dwarfs (Newton+, 2014)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/ApJ/821/93 : Rotation & Galactic kinematics of mid M dwarfs (Newton+, 2016)J/A+A/600/A13 : HARPS M dwarf sample magnetic activity (Astudillo-Defru+, 2017)J/A+A/644/A68 : Abundance signature of M dwarf stars (Maldonado+, 2020)J/MNRAS/499/5004 : K2-111, an old system with two planets (Mortier+, 2020)J/A+A/636/A74 : HARPS radial velocity database (Trifonov+, 2020)J/AJ/161/70 : RVs for WASP-107 with HIRES & CORALIE (Piaulet+, 2021)J/ApJS/255/8 : California Legacy Survey. I. Planet catalog (Rosenthal+, 2021)J/AJ/161/63 : M dwarfs with masses 0.1<M/Msun<0.3 within 15pc (Winters+, 2021)J/A+A/666/A143 : AD Leo RV and stellar activity indices (Kossakowski+, 2022)J/other/Sci/377.1211 : RV and LC of 8 M dwarf stars with planets (Luque+, 2022)J/AJ/165/88 : Radial velocity follow up of TOI-561 b (Brinkman+, 2023)J/AJ/168/67 : TOI-1450 RVs & activity indicators (Brady+, 2024)J/A+A/691/A233 : TOI-5005 b phot. & radial velocities (Castro-Gonzalez+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/170/335https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/170/335http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/170/335https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/170/335https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/170/335http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/170/335GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/170/335/tablea1MAROON-X data for GJ 12 brecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlag[0/1] 1=Excluded from RV analysis (flag) (2)meta.code.errorinte_CRX[3.57/343.56] Uncertainty in CRX (e_crx)m/sstat.error;spect.index;arith.difffloate_CaIRT3[3.1e-4/1.6e-2]? Uncertainty in IRT3 (e_irt-ind3)stat.error;spect.indexdoublenullableHalpha[0.61/0.9] H{alpha} index (halpha-v)spect.index;em.line.Halphadoublee_Halpha[1.2e-3/0.04] Uncertainty in Halpha (e_halpha-v)stat.error;spect.index;em.line.HalphadoubleNaD1[0.14/0.19]? Sodium doublet (5891.6{AA} line) index (nad1-v)spect.indexdoublenullablee_NaD1[7.2e-4/2.6e-3]? Uncertainty in NaD1 (e_nad1-v)stat.error;spect.indexdoublenullableNaD2[0.14/0.19]? Sodium doublet (5897.6{AA} line) index (nad2-v)spect.indexdoublenullablee_NaD2[7.2e-4/2.6e-3]? Uncertainty in NaD2 (e_nad2-v)stat.error;spect.indexdoublenullableArmChannel of observation, red or blue arm of MAROON-X (channel) (1)meta.id;instrcharBJD[2460530/2460682] Barycentric Julian date of observation (BJD)dtime.epochdoubleRVel[-2.55/13.04] Radial velocity (rv)m/sspect.dopplerVelocfloate_RVel[0.26/12.87] Uncertainty in RVel (e_rv)m/sstat.error;spect.dopplerVelocfloatSNR[27/405] Peak SNR of spectrum (sn-peak)stat.snr;stat.maxintExpTime[1800] Exposure time (exptime)stime.duration;obs.exposureintBERV[-29889.48/23335.19] Barycentric radial velocity (berv)m/sphys.veloc;arith.diff;pos.barycenterdoubleAM[1/2.09] Airmass of observation (airmass)obs.airMassfloatdLW[-8.39/778.52] Differential line width (dLW)spect.line.widthfloate_dLW[0.33/11.98] Uncertainty in dLW (e_dLW)stat.error;spect.line.width;arith.difffloatCRX[-20.14/239.43] Chromatic index (crx)m/sspect.indexfloatCaIRT1[0.65/0.77]? Calcium infrared triplet (8500.4{AA} line) index (irt-ind1)spect.indexdoublenullablee_CaIRT1[3.7e-4/1.6e-2]? Uncertainty in IRT1 (e_irt-ind1)stat.error;spect.indexdoublenullableCaIRT2[0.48/0.67]? Calcium infrared triplet (8544.4{AA} line) index (irt-ind2)spect.indexdoublenullablee_CaIRT2[3.2e-4/1.7e-2]? Uncertainty in IRT2 (e_irt-ind2)stat.error;spect.indexdoublenullableCaIRT3[0.44/0.74]? Calcium infrared triplet (8664.5{AA} line) index (irt-ind3)spect.indexdoublenullable