J/ApJ/652/313ivo://CDS.VizieR/J/ApJ/652/313doi:10.26093/cds/vizier.16520313CDSBonanos A.Z.Stanek K.Z.Kudritzki R.P.Macri L.M.Sasselov D.D.,Kaluzny J.Stetson P.B.Bersier D.Bresolin F.Matheson T.,Mochejska B.J.Przybilla N.Szentgyorgyi A.H.Tonry J.Torres G.2017-06-22T14:29:17Z2008-12-31T15:59:25ZCDS support team

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

cds-question@unistra.frgalaxieseclipsing-binary-starsphotometryWe present the first direct distance determination to a detached eclipsing binary in M33, which was found by the DIRECT Project. Located in the OB 66 association at coordinates (RA,DE)=(01:33:46.17,+30:44:39.9) for J2000.0, it was one of the most suitable detached eclipsing binaries found by DIRECT for distance determination, given its apparent magnitude and orbital period. We obtained follow-up BV time-series photometry, JHKs photometry, and optical spectroscopy from which we determined the parameters of the system. It contains two O7 main-sequence stars, with masses of 33.4+/-3.5 and 30.0+/-3.3M_{sun}_ and radii of 12.3+/-0.4 and 8.8+/-0.3R_{sun}_, respectively. We derive temperatures of 37000+/-1500 and 35600+/-1500K. Using BVRJHKs photometry for the flux calibration, we obtain a distance modulus of 24.92+/-0.12mag (964+/-54kpc), which is 0.3mag longer than the Key Project distance to M33. We discuss the implications of our result and the importance of establishing M33 as an independent rung on the cosmological distance ladder.2006ApJ...652..313Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/652/313CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/AJ/115/1016 : M31B eclipsing binaries and Cepheids (Kaluzny+ 1998)J/AJ/115/1894 : M31A eclipsing binaries and Cepheids (Stanek+ 1998)J/AJ/117/2810 : Eclipsing binaries and Cepheids in M31C (Stanek+, 1999)J/AJ/118/346 : M31D eclipsing binaries and Cepheids (Kaluzny+ 1999)J/AJ/118/2211 : M31F eclipsing binaries and Cepheids (Mochejska+ 1999)J/AJ/121/861 : BVI photometry of central part of M33 (Macri+, 2001)J/AJ/121/870 : BVI photometry of Variables in M33 (Macri+, 2001)J/AJ/121/2032 : Direct variables in M33A field (Mochejska+, 2001)J/AJ/122/1383 : DIRECT BVI photometry in M31 (Mochejska+, 2001)J/AJ/122/2477 : DIRECT variables in M33B field (Mochejska+, 2001)J/AJ/126/175 : M31Y eclipsing binaries and Cepheids (Bonanos+, 2003)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/652/313https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/652/313http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/652/313https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/652/313https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/652/313http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/652/313GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/652/313/table1V-Band Light CurverecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian Datedtime.epochdoubleVmagThe V band magnitudemagphot.mag;em.opt.Vfloate_VmagError in Vmagmagstat.error;phot.mag;em.opt.VfloatJ/ApJ/652/313/table2B-Band Light CurverecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian Datedtime.epochdoubleBmagThe B band magnitudemagphot.mag;em.opt.Bfloate_BmagError in Bmagmagstat.error;phot.mag;em.opt.Bfloat