J/AJ/165/235ivo://CDS.VizieR/J/AJ/165/235doi:10.26093/cds/vizier.51650235CDSMayo A.W.Dressing C.D.Vanderburg A.Fortenbach C.D.Lienhard F.,Malavolta L.Mortier A.Nunez A.Richey-Yowell T.Turtelboom E.V.,Bonomo A.S.Latham D.W.Lopez-Morales M.Shkolnik E.Sozzetti A.,Agueros M.A.Borsato L.Charbonneau D.Cosentino R.Douglas S.T.,Dumusque X.Ghedina A.Gibson R.Granata V.Harutyunyan A.,Haywood R.D.Lacedelli G.Lorenzi V.Magazzu A.,Martinez Fiorenzano A.F.Micela G.Molinari E.Montalto M.,Nardiello D.Nascimbeni V.Pagano I.Piotto G.Pino L.Poretti E.,Scandariato G.Udry S.Buchhave L.A.2024-11-06T20:17:16Z2024-01-26T07:54:43ZCDS support team

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

cds-question@unistra.frk-starsvisible-astronomyspectroscopyradial-velocityK2-136 is a late-K dwarf (0.742{+/-}0.039M{sun}) in the Hyades open cluster with three known, transiting planets and an age of 650{+/-}70Myr. Analyzing K2 photometry, we found that planets K2-136b, c, and d have periods of 8.0, 17.3, and 25.6days and radii of 1.014{+/-}0.050R{Earth}, 3.00{+/-}0.13R{Earth}, and 1.565{+/-}0.077R{Earth}, respectively. We collected 93 radial velocity (RVel) measurements with the High-Accuracy Radial-velocity Planet Searcher for the Northern hemisphere (HARPS-N) spectrograph (Telescopio Nazionale Galileo) and 22 RVs with the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) spectrograph (Very Large Telescope). Analyzing HARPS-N and ESPRESSO data jointly, we found that K2-136c induced a semi-amplitude of 5.49{+/-}0.53m/s, corresponding to a mass of 18.1{+/-}1.9M{Earth}. We also placed 95% upper mass limits on K2-136b and d of 4.3 and 3.0M{Earth}, respectively. Further, we analyzed Hubble Space Telescope and XMM-Newton observations to establish the planetary high-energy environment and investigate possible atmospheric loss. K2-136c is now the smallest planet to have a measured mass in an open cluster and one of the youngest planets ever with a mass measurement. K2-136c has ~75% the radius of Neptune but is similar in mass, yielding a density of 3.69_-0.56_^+0.67^g/cm^3^ (~2-3 times denser than Neptune). Mass estimates for K2-136b (and possibly d) may be feasible with more RV observations, and insights into all three planets' atmospheres through transmission spectroscopy would be challenging but potentially fruitful. This research and future mass measurements of young planets are critical for investigating the compositions and characteristics of small exoplanets at very early stages of their lives and providing insights into how exoplanets evolve with time.2023AJ....165..235Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/165/235CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)I/337 : Gaia DR1 (Gaia Collaboration, 2016)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)J/A+A/331/81 : Hyades membership (Perryman+ 1998)J/A+A/526/A99 : Metal-poor solar-type * spectroscopy & masses (Sousa+, 2011)J/other/Nat/486.375 : Stellar parameters of KOI stars (Buchhave+, 2012)J/ApJ/757/161 : Spectroscopy of 56 exoplanet host stars (Torres+, 2012)J/A+A/557/A70 : Evolved planet hosts - stellar parameters (Mortier+, 2013)J/A+A/555/A150 : Physical parameters cool solar-type stars (Tsantaki+, 2013)J/A+A/566/A35 : Radial velocities of HD 41248 (Santos+, 2014)J/ApJ/795/167 : Transit of PH3 b, c, d through January 2019 (Schmitt+, 2014)J/ApJS/210/25 : Transit timing variation 15 planetary pairs. II. (Xie, 2014)J/A+A/576/A94 : Northern bright planet host stars parameters (Sousa+, 2015)J/ApJS/222/14 : Planetary candidates 1st yr K2 mission (Vanderburg+, 2016)J/ApJ/825/19 : Mass-radius relationship planets with Rp<4 (Wolfgang+, 2016)J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)J/MNRAS/472/1618 : Kepler study of starspot lifetimes (Giles+, 2017)J/ApJ/879/100 : K2 rotation per Hyades & Praesepe members (Douglas+, 2019)J/AJ/158/165 : RV obs & activity indicators Kepler-538b (Mayo+, 2019)J/ApJ/872/17 : HAZMAT. V. UV & Xray evol of Kstars (Richey-Yowell+, 2019)J/A+A/624/A15 : Kepler-411 mid-transit times (Sun+, 2019)J/AJ/160/192 : Photometry and RVs of K2-25b with HPF (Stefansson+, 2020)J/A+A/650/A66 : DS Tuc A radial velocity curve (Benatti+, 2021)J/A+A/653/A41 : L 98-59 (TOI-175) ESPRESSO observations (Demangeon+, 2021)J/A+A/649/A6 : Gaia Catalogue of Nearby Stars (Gaia collaboration, 2021)J/A+A/661/A23 : Exoplanet Xray irradiation &evaporation rate (Foster+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/165/235https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/165/235http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/165/235https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/165/235https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/165/235http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/165/235GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/165/235/table2Radial velocity observations and activity indicatorsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJD[2.4e+06/2.5e+06] Barycentric Julian Date at TBDdtime.epochdoubleRVel[39480/39519] Radial velocitym/sspect.dopplerVelocdoublee_RVel[0.4/6] Error on RVelm/sstat.error;spect.dopplerVelocfloatCCFBIS[6886/6997] Cross Correlation Function bisector span inverse slopem/sphys.velocfloate_CCFBIS[0.9/12] Error on CCFBISm/sstat.errorfloatCCFFWHM[34.1/86.1] Cross Correlation Function full width at half maximumm/sphys.velocfloate_CCFFWHM[0.9/12] Error on CCFFWHMm/sstat.errorfloatSHK[1.05/1.41] Mt. Wilson CaII HK activity indexmeta.code.multipdoublee_SHK[0.0006/0.2] Error on SHKstat.errordoubleInstInstrument used; ESPRESSO or HARPS-Ninstr.setupchar