J/ApJ/875/L13ivo://CDS.VizieR/J/ApJ/875/L13doi:10.26093/cds/vizier.18759013CDSWang M.Y.Koposov S.Drlica-Wagner A.Pieres A.Li T.S.de Boer T.,Bechtol K.Belokurov V.Pace A.B.Bacon D.Abbott T.M.C.Annis J.,Bertin E.Brooks D.Buckley-Geer E.Burke D.L.Carnero Rosell A.,Carrasco Kind M.Carretero J.da Costa L.N.De Vicente J.Desai S.,Diehl H.T.Doel P.Estrada J.Flaugher B.Fosalba P.Frieman J.,Garcia-Bellido J.Gerdes D.W.Gruen D.Gruendl R.A.Gschwend J.,Gutierrez G.Hollowood D.L.Honscheid K.Hoyle B.James D.J.Kent S.,Kuehn K.Kuropatkin N.Maia M.A.G.Marshall J.L.Menanteau F.,Miquel R.Plazas A.A.Sanchez E.Santiago B.Scarpine V.Schindler R.,Schubnell M.Serrano S.Sevilla-Noarbe I.Smith M.Smith R.C.,Sobreira F.Suchyta E.Swanson M.E.C.Tarle G.Thomas D.Tucker D.L.,Walker A.R. (The DES Collaboration).2021-09-16T09:55:41Z2020-10-21T15:28:59ZCDS support team

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

cds-question@unistra.frinfrared-photometryvisible-astronomyphotometryglobular-star-clustersSince first noticed by Shapley in 1939, a faint object coincident with the Fornax dwarf spheroidal has long been discussed as a possible sixth globular cluster (GC) system. However, debate has continued over whether this overdensity is a statistical artifact or a blended galaxy group. In this Letter we demonstrate, using deep DECam imaging data, that this object is well resolved into stars and is a bona fide star cluster. The stellar overdensity of this cluster is statistically significant at the level of ~6-6.7{sigma} in several different photometric catalogs including Gaia. Therefore, it is highly unlikely to be caused by random fluctuation. We show that Fornax 6 is a star cluster with a peculiarly low surface brightness and irregular shape, which may indicate a strong tidal influence from its host galaxy. The Hess diagram of Fornax 6 is largely consistent with that of Fornax field stars, but it appears to be slightly bluer. However, it is still likely more metal-rich than most of the GCs in the system. Faint clusters like Fornax 6 that orbit and potentially get disrupted in the centers of dwarf galaxies can prove crucial for constraining the dark matter distribution in Milky Way satellites.2019ApJ...875L..13Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/875/L13CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/350 : VLT Survey Telescope ATLAS (Shanks+, 2015)II/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018)I/345 : Gaia DR2 (Gaia Collaboration, 2018)VII/195 : Globular Clusters in the Milky Way (Harris, 1996)VII/202 : Globular Clusters in the Milky Way (Harris, 1997)J/PASP/110/533 : BR photometry of Fornax bright stars (Stetson+ 1998)J/ApJS/161/304 : Star clusters in the MW and satellites (McLaughlin+, 2005)J/A+A/459/423 : VI and [Fe/H] of Fornax dSph RGB stars (Battaglia+, 2006)J/AJ/137/3100 : Radial velocities of 4 dSph galaxies (Walker+, 2009)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/MNRAS/453/690 : Fornax VST ATLAS catalogue (Bate+, 2015)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/875/L13https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/875/L13http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/875/L13https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/875/L13https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/875/L13http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/875/L13GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/875/L13/fig3 (Fornax 6 positions and r and i magnitudes)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/875/L13/fig3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/875/L13/fig3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/875/L13/fig3?GETtext/xml+votable180.050000true40.065311076-34.4634407940.0055555555555555566/359692.3230668610021367e-19 3.508503837478091e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/875/L13?format=asciiOpticalInfrareddefaultJ/ApJ/875/L13/fig3Fornax 6 positions and r and i magnitudesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainrmag[15.6/30.6] CTIO/DECam r band (AB) magnitudemagphot.mag;em.opt.Rdoubleimag[16.5/29.5] CTIO/DECam i band (AB) magnitudemagphot.mag;em.opt.IdoubleDESDisplay data from DES DR1 (II/357) within 0.5"meta.ref.urlnullable