J/AJ/159/2ivo://CDS.VizieR/J/AJ/159/2doi:10.26093/cds/vizier.51590002CDSPetigura E.A.Livingston J.Batygin K.Mills S.M.Werner M.,Isaacson H.Fulton B.J.Howard A.W.Weiss L.M.Espinoza N.,Jontof-Hutter D.Shporer A.Bayliss D.Barros S.C.C.2020-02-14T06:29:01Z2020-02-13T14:07:56ZCDS support team

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

cds-question@unistra.frexoplanetsradial-velocitymultiple-starsK2-19b and c were among the first planets discovered by NASA's K2 mission and together stand in stark contrast with the physical and orbital properties of the solar system planets. The planets are between the size of Uranus and Saturn at 7.0+/-0.2 R_{Earth}_ and 4.1+/-0.2 R_{Earth}_, respectively, and reside a mere 0.1% outside the nominal 3:2 mean-motion resonance. They represent a different outcome of the planet formation process than the solar system, as well as the vast majority of known exoplanets. We measured the physical and orbital properties of these planets using photometry from K2, Spitzer, and ground-based telescopes, along with radial velocities from Keck/HIRES. Through a joint photodynamical model, we found that the planets have moderate eccentricities of e~0.20 and well-aligned apsides {Delta}{omega}~0{deg}. The planets occupy a strictly nonresonant configuration: the resonant angles circulate rather than librate. This defies the predictions of standard formation pathways that invoke convergent or divergent migration, both of which predict {Delta}{omega}~180{deg} and eccentricities of a few percent or less. We measured masses of M_p,b_=32.4+/-1.7 M_{Earth}_ and M_p,c_=10.8+/-0.6 M_{Earth}_. Our measurements, with 5% fractional uncertainties, are among the most precise of any sub-Jovian exoplanet. Mass and size reflect a planet's core/envelope structure. Despite having a relatively massive core of M_core_~15 M_{Earth}_, K2-19b is envelope-rich, with an envelope mass fraction of roughly 50%. This planet poses a challenge to standard models of core-nucleated accretion, which predict that cores >~10 M_{Earth}_ will quickly accrete gas and trigger runaway accretion when the envelope mass exceeds that of the core.2020AJ....159....2Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/159/2CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/579/A19 : K2 Variable Catalogue (Armstrong+, 2015)J/A+A/601/A128 : K2-19b and K2-19c radial velocity curves (Nespral+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/159/2https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/159/2http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/159/2https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/159/2https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/159/2http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/159/2GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/AJ/159/2/table2Radial velocitiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJD[2225/3281.12] Barycentric Dynamical Time, BJD_TBD_-2454833dtime.epochdoubleRV[-27.89/15.11] Relative radial velocity with respect to solar system barycenterm/sphys.veloc;pos.heliocentricfloate_RV[1.89/3.79] Uncertainty in RVm/sstat.errorfloatSHK[0.181/0.401] Mount Wilson S_HK_ activity indexspect.indexfloatJ/AJ/159/2/table4Predicted transit timesi[0/718] Transit indexmeta.numberintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPlanet[bc] K2-19 planetmeta.id;meta.maincharDatePredicted transit date, UTCtime.epochnullableTc[1980.38/7667.37] Predicted transit time, BJD_TBD_-2454833dtime.epochdoublee_Tc[0.0001/0.3689] Uncertainty in Tcdstat.errorfloatJ/AJ/159/2/table1Transit timesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPlanetPlanet (K2-19b or K2-19c)meta.id;meta.maincharTransit[30/150] Kepler transit numbermeta.idintInstInstrumentmeta.id;instrcharTc[2218/3197.87] Transit time, BJD_TBD_-2454833dtime.epochdoublee_Tc[0.0009/0.0074] Uncertainty in Tcdstat.errorfloatr_Tc[AB] Reference for Tc (1)meta.ref;pos.framechar