J/AJ/166/49ivo://CDS.VizieR/J/AJ/166/49doi:10.26093/cds/vizier.51660049CDSDai F.Schlaufman K.C.Reggiani H.Bouma L.Howard A.W.Chontos A.,Pidhorodetska D.Van Zandt J.Akana Murphy J.M.Rubenzahl R.A.,Polanski A.S.Lubin J.Beard C.Giacalone S.Holcomb R.Batalha N.M.,Crossfield I.Dressing C.Fulton B.Huber D.Isaacson H.Kane S.R.,Petigura E.A.Robertson P.Weiss L.M.Belinski A.A.Boyle A.W.,Burke C.J.Castro-Gonzalez A.Ciardi D.R.Daylan T.Fukui A.Gill H.,Guerrero N.M.Hellier C.Howell S.B.Lillo-Box J.Murgas F.,Narita N.Palle E.Rodriguez D.R.Savel A.B.Shporer A.Stassun K.G.,Striegel S.Caldwell D.A.Jenkins J.M.Ricker G.R.Seager S.,Vanderspek R.Winn J.N.2024-11-06T20:18:46Z2024-02-23T09:17:05ZCDS support team

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

cds-question@unistra.frexoplanetsk-starsvisible-astronomyspectroscopyWe report the discovery and Doppler mass measurement of a 7.4days 2.3R{Earth} mini-Neptune around a metal-poor K-dwarf BD+29-2654 (TOI-2018). Based on a high-resolution Keck/HIRES spectrum, the Gaia parallax, and multiwavelength photometry from the UV to the mid-infrared, we found that the host star has Teff=4174_-42_^+34^K, logg=4.62_-0.03_^+0.02^, [Fe/H]=-0.58{+/-}0.18, M*=0.57{+/-}0.02M{sun}, and R*=0.62{+/-}0.01R{sun}. Precise Doppler measurements with Keck/HIRES revealed a planetary mass of Mp=9.2{+/-}2.1M{Earth} for TOI-2018b. TOI-2018b has a mass and radius that are consistent with an Earthlike core, with a ~1%-by-mass hydrogen/helium envelope or an ice-rock mixture. The mass of TOI-2018b is close to the threshold for runaway accretion and hence giant planet formation. Such a threshold is predicted to be around 10M{Earth} or lower for a low-metallicity (low-opacity) environment. If TOI-2018b is a planetary core that failed to undergo runaway accretion, it may underline the reason why giant planets are rare around low- metallicity host stars (one possibility is their shorter disk lifetimes). With a K-band magnitude of 7.1, TOI-2018b may be a suitable target for transmission spectroscopy with the James Webb Space Telescope. The system is also amenable to metastable Helium observation; the detection of a Helium exosphere would help distinguish between a H/He-enveloped planet and a water world.2023AJ....166...49Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/166/49CatalogResearchIsServedByTAP VizieR generic servicerelated-toI/337 : Gaia DR1 (Gaia Collaboration, 2016)I/345 : Gaia DR2 (Gaia Collaboration, 2018)IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)VI/39 : Model Atmospheres (Kurucz, 1979)J/A+A/415/1153 : [Fe/H] for 98 extra-solar planet-host stars (Santos+, 2004)J/ApJ/622/1102 : The planet-metallicity correlation. (Fischer+, 2005)J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)J/ApJ/728/117 : Kepler planetary candidates. I. (Borucki+, 2011)J/AJ/142/19 : Speckle observations of KOI (Howell+, 2011)J/A+A/562/A71 : Abundances of solar neighbourhood dwarfs (Bensby+, 2014)J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)J/AJ/152/180 : Bolometric fluxes clipsing binaries Tycho-2 (Stassun+, 2016)J/AJ/154/226 : Photometry and radial velocities of K2-131 (Dai+, 2017)J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)J/AJ/153/71 : Kepler follow-up observation program. I. (Furlan+, 2017)J/ApJ/844/102 : KIC parallaxes from asteroseismology vs Gaia (Huber+, 2017)J/ApJ/856/23 : BANYAN. XI. The BANYAN {Sigma} algorithm (Gagne+, 2018)J/AJ/155/89 : California-Kepler Survey (CKS). IV. Planets (Petigura+, 2018)J/A+A/630/A89 : WASP-12b and WASP-43b griz light curves (Parviainen+, 2019)J/AN/341/996 : Stellar companions of (C)TOIs (Mugrauer+, 2020)J/AJ/159/19 : SOAR TESS survey. I. (Ziegler+, 2020)J/MNRAS/506/150 : The GALAH+ Survey DR3 (Buder+, 2021)J/A+A/653/A41 : L 98-59 (TOI-175) ESPRESSO observations (Demangeon+, 2021)J/ApJS/254/39 : Exoplanet candidates from TESS 1st 2yr obs (Guerrero+, 2021)J/AN/342/840 : Stellar companions of (C)TOIs (Mugrauer+, 2021)J/AJ/164/215 : Candidate members of Cep-Her, RSG-5 and CH-2 (Bouma+, 2022)J/other/Sci/377.1211 : RV and LC of 8 M dwarf stars with planets (Luque+, 2022)J/AJ/163/159 : Species abundances in WASP-77A (Reggiani+, 2022)J/MNRAS/511/1043 : Sub-Neptunes transiting TOI-1064 (Wilson+, 2022)J/AJ/165/88 : Radial velocity follow up of TOI-561 b (Brinkman+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/166/49https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/166/49http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/166/49https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/166/49https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/166/49http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/166/49GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/166/49/table2Atomic data, equivalent Widths and line abundancesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWave[4470/7934] Wavelength; Angstroms0.1nmem.wldoubleSpeciesSpecies identifiermeta.id;meta.maincharExPot[0.12/5.11] Excitation potentialeVphys.atmol.excitationfloatloggf[-5.34/0.5] log oscillator strengthphys.atmol.oscStrengthfloatEW[1.7/170] Equivalent width; milli-Angstroms1e-13mspect.line.eqWidthfloatlogX[1.26/7.5] log number abundancephys.abund.Xfloat