J/ApJ/900/L44ivo://CDS.VizieR/J/ApJ/900/L44doi:10.26093/cds/vizier.19009044CDSKipping D.2022-05-18T14:35:19Z2022-02-15T13:58:34ZCDS support team

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

cds-question@unistra.frexoplanetsphotometryIt has been recently claimed that KOIs-268.01, 303.01, 1888.01, 1925.01, 2728.01, and 3320.01 are exomoon candidates, based on an analysis of their transit timing. Here, we perform an independent investigation, which is framed in terms of three questions: (1) Are there significant transit timing variations (TTVs)? (2) Is there a significant periodic TTV? (3) Is there evidence for a nonzero moon mass? We applied rigorous statistical methods to these questions alongside a reanalysis of the Kepler photometry and find that none of the Kepler objects of interest (KOIs) satisfy our three tests. Specifically, KOIs-268.01 and 3220.01 pass none of the tests and KOIs-303.01, 1888.01, and 1925.01 pass a single test each. Only KOI-2728.01 satisfies two, but fails the cross-validation test for predictions. Further, detailed photodynamical modeling reveals that KOI-2728.01 favors a negative-radius moon (as does KOI-268.01). We also note that we find a significant photoeccentric effect for KOI-1925.01 indicating an eccentric orbit of at least e>(0.62+/-0.06). For comparison, we applied the same tests to Kepler-1625b, which reveals that (1) and (3) are passed, but (2) cannot be checked with the cross- validation method used here, due to the limited number of available epochs. In conclusion, we find no compelling evidence for exomoons among the six KOIs. Despite this, we were able to derive exomoon mass upper limits versus semimajor axis, with KOI-3220.01 leading to particularly impressive constraints of MS/MP<0.4% [2{sigma}] at a similar semimajor to that of the Earth-Moon.2020ApJ...900L..44Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/900/L44CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/208/16 : Kepler transit timing observations. VIII. (Mazeh+, 2013)J/ApJS/225/9 : Kepler TTVs. IX. Full long-cadence data set (Holczer+, 2016)J/ApJS/229/30 : Revised properties of Q1-17 Kepler targets (Mathur+, 2017)J/AJ/154/5 : Transit timing variations of 145 Kepler planets (Hadden+, 2017)J/ApJS/234/9 : A spectral approach to transit timing variations (Ofir+, 2018)J/A+A/615/A79 : KOINet. Study of exoplanet systems via TTVs (von Essen+, 2018)J/ApJ/887/261 : Compil. of planets around M dwarfs (Martinez-Rodriguez+, 2019)J/other/RAA/19.41 : TTVs of Kepler exoplanets (Gajdos+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/900/L44https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/900/L44http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/900/L44https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/900/L44https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/900/L44http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/900/L44GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/900/L44/table1 (Statistical tests for evidence for exomoons, using gravitational effects only (Section 3))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/900/L44/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/900/L44/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/900/L44/table1?GETtext/xml+votable180.050000true285.728800838.50696780.0055555555555555566/14731 14752 14760 14921 15121 15129 15139https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/900/L44?format=asciidefaultJ/ApJ/900/L44/table1Statistical tests for evidence for exomoons, using gravitational effects only (Section 3)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameName of the sourcemeta.id;meta.maincharprimaryBIC[-32.3/93.9] Bayesian information criterion, BIC_P,T_stat.fit.paramfloatn_BICAre there statistically significant TTVs? (Yes/No)meta.notecharGood[0/54]? Percentage of Good TTV predictions%stat.fit.paramintnullablen_GoodIs there a statistically significant periodic TTV? (Yes/No)meta.notecharlogK[-6.9/1.9] logK_M:X_ value (see Figure 2)stat.fit.paramfloatn_logKDo the observations support a statistically significant nonzero moon mass? (Yes/No)meta.notecharMs/Mp[0.39/5.9]? Ms to Mp ratio upper limit at 60Rp, 2{sigma}%stat.fit.paramfloatnullableNmNumber of measurements for this source (link to fig1.dat)meta.numberintnullablePlotInteractive TTV plotmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar_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/ApJ/900/L44/fig1Transit timing variations (TTVs) for the six claimed exomoon candidate hostsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource identifiermeta.id;meta.maincharEpoch[0/34] Epoch numbermeta.idinttau[-33/1408] Median reference time of transit minimum (1)time.epoch;stat.mediandoublee_tau[0.00077/0.0071] Lower 34.1% uncertainty in taustat.errordoubleE_tau[0.00095/0.007] Upper 34.1% uncertainty in taustat.error;stat.maxdoubleTTV[-20/35] Median Transit timing variation (1)minstat.fit.residualfloate_TTV[1/10] Lower 34.1% uncertainty in TTVminstat.errorfloatE_TTV[1.4/9.7] Upper 34.1% uncertainty in TTVminstat.error;stat.maxfloat