J/ApJ/728/138ivo://CDS.VizieR/J/ApJ/728/138doi:10.26093/cds/vizier.17280138CDSHartman J.D.Bakos G.A.Kipping D.M.Torres G.Kovacs G.Noyes R.W.,Latham D.W.Howard A.W.Fischer D.A.Johnson J.A.Marcy G.W.,Isaacson H.Quinn S.N.Buchhave L.A.Beky B.Sasselov D.D.,Stefanik R.P.Esquerdo G.A.Everett M.Perumpilly G.Lazar J.Papp I.,Sari P.2017-06-19T07:58:10Z2012-10-22T12:58:28ZCDS support team

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

cds-question@unistra.frccd-photometrysolar-system-planetsmultiple-starsWe report the discovery of HAT-P-26b, a transiting extrasolar planet orbiting the moderately bright V=11.744 K1 dwarf star GSC 0320-01027, with a period P=4.234516+/-0.000015 days, transit epoch T_c_=2455304.65122+/-0.00035 (BJD; Barycentric Julian dates throughout the paper are calculated from Coordinated Universal Time (UTC)), and transit duration 0.1023+/-0.0010 days. The host star has a mass of 0.82+/-0.03M_{sun}_, radius of 0.79^+0.10^_-0.04_R_{sun}_, effective temperature 5079+/-88K, and metallicity [Fe/H]=-0.04+/-0.08. The planetary companion has a mass of 0.059+/-0.007M_J_, and radius of 0.565^+0.072^_-0.032_R_J_ yielding a mean density of 0.40+/-0.10g/cm^3^. HAT-P-26b is the fourth Neptune-mass transiting planet discovered to date. It has a mass that is comparable to those of Neptune and Uranus, and slightly smaller than those of the other transiting Super-Neptunes, but a radius that is ~65% larger than those of Neptune and Uranus, and also larger than those of the other transiting Super-Neptunes. HAT-P-26b is consistent with theoretical models of an irradiated Neptune-mass planet with a 10M_{earth}_ heavy element core that comprises >~50% of its mass with the remainder contained in a significant hydrogen-helium envelope, though the exact composition is uncertain as there are significant differences between various theoretical models at the Neptune-mass regime. The equatorial declination of the star makes it easily accessible to both Northern and Southern ground-based facilities for follow-up observations.2011ApJ...728..138Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/728/138CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/eso : ESO Science Archive Catalog (ESO, 2012)B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2012)J/MNRAS/422/2024 : X-age relation and exoplanet evaporation (Jackson+, 2012)J/ApJ/694/1559 : Photometric follow-up of GJ 436b (Shporer+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/728/138https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/728/138http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/728/138https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/728/138https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/728/138http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/728/138GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/ApJ/728/138/table3High-precision differential photometry of HAT-P-26recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBaryocentric Julian Date (BJD-2400000)dtime.epochdoublemagProcessed magnitude in Filter (1)magphot.mag;em.opt.Idoublee_magThe 1{sigma} error in magmagstat.error;phot.magdoubleOmagOriginal magnitude in Filter (2)magphot.mag;em.opt.IdoubleFilt[i] Filter used in the observation (i-band)instr.setup;obschar