J/ApJ/795/64ivo://CDS.VizieR/J/ApJ/795/64doi:10.26093/cds/vizier.17950064CDSForeman-Mackey D.Hogg D.W.Morton T.D.2017-07-18T15:22:33Z2017-05-31T14:58:05ZCDS support team

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

cds-question@unistra.frmultiple-starssolar-system-planetsastronomical-modelsNo true extrasolar Earth analog is known. Hundreds of planets have been found around Sun-like stars that are either Earth-sized but on shorter periods, or else on year-long orbits but somewhat larger. Under strong assumptions, exoplanet catalogs have been used to make an extrapolated estimate of the rate at which Sun-like stars host Earth analogs. These studies are complicated by the fact that every catalog is censored by non-trivial selection effects and detection efficiencies, and every property (period, radius, etc.) is measured noisily. Here we present a general hierarchical probabilistic framework for making justified inferences about the population of exoplanets, taking into account survey completeness and, for the first time, observational uncertainties. We are able to make fewer assumptions about the distribution than previous studies; we only require that the occurrence rate density be a smooth function of period and radius (employing a Gaussian process). By applying our method to synthetic catalogs, we demonstrate that it produces more accurate estimates of the whole population than standard procedures based on weighting by inverse detection efficiency. We apply the method to an existing catalog of small planet candidates around G dwarf stars. We confirm a previous result that the radius distribution changes slope near Earth's radius. We find that the rate density of Earth analogs is about 0.02 (per star per natural logarithmic bin in period and radius) with large uncertainty. This number is much smaller than previous estimates made with the same data but stronger assumptions.2014ApJ...795...64Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/795/64CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJ/646/505 : Catalog of nearby exoplanets (Butler+, 2006)J/AJ/151/59 : Catalog of Earth-Like Exoplanet Survey Targetshttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/795/64https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/795/64http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/795/64https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/795/64https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/795/64http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/795/64GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/ApJ/795/64/fig1Simulated data for Catalog ArecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPerPerioddtime.perioddoubleRad[] Radius in Earth radii(6.3781x10+6m)phys.size.radius;arith.ratiodoublee_RadUncertainty in Rad(6.3781x10+6m)stat.errordoubleJ/ApJ/795/64/fig2Simulated data for Catalog BrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPerPerioddtime.perioddoubleRad[] Radius in Earth radii(6.3781x10+6m)phys.size.radius;arith.ratiodoublee_RadUncertainty in Rad(6.3781x10+6m)stat.errordouble