J/MNRAS/466/1868ivo://CDS.VizieR/J/MNRAS/466/1868doi:10.26093/cds/vizier.74661868CDSCubillos P.Erkaev N.V.Juvan I.Fossati L.Johnstone C.P.Lammer H.,Lendl M.Odert P.Kislyakova K.G.2024-08-17T20:17:40Z2019-11-27T14:22:05ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsgalaxy-classification-systemsstellar-mass-lossWe present a uniform analysis of the atmospheric escape rate of Neptune-like planets with estimated radius and mass (restricted to M_p_<30M_{Earth}_). For each planet, we compute the restricted Jeans escape parameter, {Lambda}, for a hydrogen atom evaluated at the planetary mass, radius, and equilibrium temperature. Values of {Lambda}<=20 suggest extremely high mass-loss rates. We identify 27 planets (out of 167) that are simultaneously consistent with hydrogen-dominated atmospheres and are expected to exhibit extreme mass-loss rates. We further estimate the mass-loss rates (L_hy_) of these planets with tailored atmospheric hydrodynamic models. We compare L_hy_ to the energy-limited (maximum-possible high-energy driven) mass-loss rates. We confirm that 25 planets (15 per cent of the sample) exhibit extremely high mass-loss rates (L_hy_>0.1M_{Earth}_/Gyr), well in excess of the energy-limited mass-loss rates. This constitutes a contradiction, since the hydrogen envelopes cannot be retained given the high mass-loss rates. We hypothesize that these planets are not truly under such high mass-loss rates. Instead, either hydrodynamic models overestimate the mass-loss rates, transit-timing-variation measurements underestimate the planetary masses, optical transit observations overestimate the planetary radii (due to high-altitude clouds), or Neptunes have consistently higher albedos than Jupiter planets. We conclude that at least one of these established estimations/techniques is consistently producing biased values for Neptune planets. Such an important fraction of exoplanets with misinterpreted parameters can significantly bias our view of populations studies, like the observed mass-radius distribution of exoplanets for example.2017MNRAS.466.1868Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/466/1868CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/466/1868https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/466/1868http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/466/1868https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/466/1868https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/466/1868http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/466/1868GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/466/1868/tablea1 (*Observed and derived parameters for the sub-Neptune planet sample.)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/466/1868/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/466/1868/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/466/1868/tablea1?GETtext/xml+votable180.050000true133.149212228.33081970.0055555555555555565/3734 6/413 4651 5009 14278 14582 14585 14587 14591 14733-14735 14744 14751 14753 14757 14759 14762-14764 14767-14768 14774 14778 14781 14794 14824-14825 14918-14920 14923-14925 14930 14932-14933 14935 14952 14958 14960 14962 14965-14966 14969 14973 15060 15104-15105 15108-15110 15115-15116 15118 15120-15121 15123 15126-15127 15131 15134 15136-15137 15143 15149 15158 15169-15172 18569 18800 22065 22078 26062 26977 26992 28400 28548 30450 31216 38464 42986https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/466/1868?format=asciiOpticaldefaultJ/MNRAS/466/1868/tablea1*Observed and derived parameters for the sub-Neptune planet sample.SimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameNamemeta.id;meta.maincharMpPlanetary mass(5.97236x10+24kg)phys.massfloatE_MpError on Mp (upper value)(5.97236x10+24kg)stat.error;stat.maxfloate_MpError on Mp (lower value)(5.97236x10+24kg)stat.errorfloatRpPlanetary radius(6.3781x10+6m)phys.angSize;srcfloatE_RpError on Rp (upper value)(6.3781x10+6m)stat.error;stat.maxfloate_RpError on Rp (lower value)(6.3781x10+6m)stat.errorfloatTeqEquilibrium temperature (1)Kphys.temperatureintLambdaRestricted Jeans escape parameter (comes from equation (1))stat.fit.paramfloatrhopPlanetary mean density (2)g.cm**-3phys.density;stat.meanfloataOrbital semimajor axisauphys.angSize.smajAxis;src.orbitalfloatMsStellar masssolMassphys.massfloatAge? AgeGyrtime.agefloatnullableOmegarot? Rotational angular velocity, in solar unitSunphys.veloc.angfloatnullableFXUVStellar XUV-flux received by the planet for the given orbital semimajor axis (a), stellar mass (Ms), age, and rotational angular velocity (Omegarot)mW.m**-2phot.flux;em.X-raydoubleLhy? Hydrodynamic mass-loss rate (3)s**-1phot.count;em.X-raydoublenullableLen? Energy-limited XUV-driven mass-loss rate (3)s**-1phot.count;em.X-raydoublenullableLhy/Len? Ratio for hydrodynamic to energy-limited XUV-driven mass-loss ratesphot.count;arith.ratiodoublenullableRefReferences for Planetary Masses and Radii, in refs.dat filemeta.refcharNote[R,T ] R and T indicate RV- and TTV-estimated mass, respectivelymeta.notechar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/MNRAS/466/1868/refsReferencesComCommentsmeta.notecharAutAuthor's namemeta.bib.authorcharRefReference codemeta.note;meta.maincharprimaryBibCodeBibCodemeta.bib.bibcodecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint