J/AJ/162/79ivo://CDS.VizieR/J/AJ/162/79doi:10.26093/cds/vizier.51620079CDSCloutier R.Charbonneau D.Stassun K.G.Murgas F.Mortier A.,Massey R.Lissauer J.J.Latham D.W.Irwin J.Haywood R.D.Guerra P.,Girardin E.Giacalone S.A.Bosch-cabot P.Bieryla A.Winn J.,Watson C.A.Vanderspek R.Udry S.Tamura M.Sozzetti A.Shporer A.,Segransan D.Seager S.Savel A.B.Sasselov D.Rose M.Ricker G.,Rice K.Quintana E.V.Quinn S.N.Piotto G.Phillips D.Pepe F.,Pedani M.Parviainen H.Palle E.Narita N.Molinari E.Micela G.,Mcdermott S.Mayor M.Matson R.A.Martinez Fiorenzano A.F.Lovis C.,Lopez-morales M.Kusakabe N.Jensen E.L.N.Jenkins J.M.Huang C.X.,Howell S.B.Harutyunyan A.Furesz G.Fukui A.Esquerdo G.A.,Esparza-borges E.Dumusque X.Dressing C.D.Di Fabrizio L.,Collins K.A.Cameron A.C.Christiansen J.L.Cecconi M.Buchhave L.A.,Boschin W.Andreuzzi G.2024-11-25T09:05:03Z2021-12-07T09:07:10ZCDS support team

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

cds-question@unistra.frexoplanetsm-starsdwarf-starsvisible-astronomyspectroscopyradial-velocityStudies of close-in planets orbiting M dwarfs have suggested that the M-dwarf radius valley may be well explained by distinct formation timescales between enveloped terrestrials and rocky planets that form at late times in a gas-depleted environment. This scenario is at odds with the picture that close-in rocky planets form with a primordial gaseous envelope that is subsequently stripped away by some thermally driven mass-loss process. These two physical scenarios make unique predictions of the rocky/enveloped transition's dependence on orbital separation such that studying the compositions of planets within the M-dwarf radius valley may be able to establish the dominant physics. Here, we present the discovery of one such keystone planet: the ultra-short-period planet TOI-1634b (P=0.989days, F=121F{Earth}, r_p_=1.790_-0.081_^+0.080^R{Earth}) orbiting a nearby M2 dwarf (K_s_=8.7, R_s_=0.450R{sun}, M_s_=0.502M{sun}) and whose size and orbital period sit within the M-dwarf radius valley. We confirm the TESS-discovered planet candidate using extensive ground-based follow-up campaigns, including a set of 32 precise radial velocity measurements from HARPS-N. We measure a planetary mass of 4.91_-0.70_^+0.68^M{Earth}, which makes TOI-1634b inconsistent with an Earth-like composition at 5.9{sigma} and thus requires either an extended gaseous envelope, a large volatile-rich layer, or a rocky composition that is not dominated by iron and silicates to explain its mass and radius. The discovery that the bulk composition of TOI-1634b is inconsistent with that of Earth supports the gas-depleted formation mechanism to explain the emergence of the radius valley around M dwarfs with M_s_<~0.5M{sun}.2021AJ....162...79Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/162/79CatalogResearchIsServedByTAP VizieR generic servicerelated-toI/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)J/ApJ/720/1118 : i-band photometry of HAT-P-16 (Buchhave+, 2010)J/A+A/529/A75 : Limb-darkening coefficients (Claret+, 2011)J/AJ/142/19 : Speckle observations of KOI (Howell+, 2011)J/ApJS/200/15 : HARPS-TERRA project. I. (Anglada-Escude+, 2012)J/A+A/549/A109 : HARPS XXXI. The M-dwarf sample (Bonfils+, 2013)J/ApJS/208/9 : Intrinsic colors and temperatures of PMS stars (Pecaut+, 2013)J/AJ/148/64 : HAZMAT. I. FUV & NUV emission in early M stars (Shkolnik+, 2014)J/A+A/573/A101 : Generalised Lomb-Scargle periodogram code (Mortier+, 2015)J/A+A/575/A119 : HARPS RV and stellar activity (Astudillo-Defru+, 2015)J/ApJ/804/64 : Empirical and model parameters of 183 M dwarfs (Mann+, 2015)J/ApJ/807/45 : Potentially habitable planets orbiting Mdwarfs (Dressing+, 2015)J/AJ/152/141 : Solar neighborhood. XXXVII. RVs for M dwarfs (Benedict+, 2016)J/AJ/152/180 : Bolometric fluxes eclipsing binaries in Tycho-2 (Stassun+, 2016)J/MNRAS/457/2877 : Kepler M dwarf stars revised properties (Gaidos+, 2016)J/A+A/600/A13 : HARPS M dwarf sample magnetic activity (Astudillo-Defru+, 2017)J/AJ/153/136 : Planets and their host stars with Gaia plxes (Stassun+, 2017)J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)J/AJ/154/237 : HARPS-N radial velocities of WASP-47 (Vanderburg+, 2017)J/ApJ/834/85 : H{alpha} emission in nearby M dwarfs (Newton+, 2017)J/A+A/618/A142 : Radial velocity for GJ 1132 (Bonfils+, 2018)J/A+A/619/A1 : 55 Cnc radial velocities and photometry (Bourrier+, 2018)J/AJ/156/264 : California-Kepler Survey. VII. Planet radius gap (Fulton+, 2018)J/AJ/156/18 : APOGEE DR14:Binary comp. of evolved stars (Price-Whelan+, 2018)J/A+A/621/A49 : K2-18 HARPS time-series (Cloutier+, 2019)J/A+A/628/A39 : Radial velocities of GJ 357 (Luque+, 2019)J/A+A/629/A111 : L 98-59 (TOI 175) HARPS observations (Cloutier+, 2019)J/A+A/630/A89 : WASP-12b and WASP-43b griz light curves (Parviainen+, 2019)J/AJ/158/75 : Mid-type M dwarfs planet occur. rates (Hardegree-Ullman+, 2019)J/ApJ/875/29 : Spectroscopic analysis of the CKS sample. I. (Martinez+, 2019)J/A+A/642/A236 : GJ 3473 (TOI-488) radial velocity curve (Kemmer+, 2020)J/AN/341/996 : Stellar companions of (C)TOIs (Mugrauer+, 2020)J/AJ/159/211 : Exoplanet parameters from Kepler and K2 (Cloutier+, 2020)J/AJ/160/3 : Radial velocities of M-dwarf LTT 3780 with HARPS (Cloutier+, 2020)J/AJ/160/22 : TOI-1235 Radial velocities & optical spectro. (Cloutier+, 2020)J/A+A/649/A3 : Gaia Early Data Release 3 photometric passbands (Riello+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/162/79https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/162/79http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/162/79https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/162/79https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/162/79http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/162/79GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/162/79/table3HARPS-N time series of TOI-1634recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJD[2068/2279] Observation time; BJD-2457000dtime.epochdoubleRVel[-12.1/7.34] HARPS-N barycentric radial velocitym/sphys.veloc;pos.heliocentricfloate_RVel[1/3] Uncertainty in RVelm/sstat.error;spect.dopplerVelocfloatFWHM[2.96/3.08] FWHMkm/sspect.line.widthfloatBIS[-13.6/8.78] HARPS cross-correlation function bisector spankm/sstat.fit.paramfloatHalpha[0.86/0.92] H{alpha} index, unitlessspect.indexfloatNaD1[0.44/0.55] Sodium doublet index, Na D1, 5890Aspect.indexfloatNaD2[0.58/0.68] Sodium doublet index, Na D2, 5896Aspect.indexfloat