J/ApJ/837/54ivo://CDS.VizieR/J/ApJ/837/54doi:10.26093/cds/vizier.18370054CDSCole A.A.Weisz D.R.Skillman E.D.Leaman R.Williams B.F.,Dolphin A.E.Johnson L.C.McConnachie A.W.Boylan-Kolchin M.,Dalcanton J.Governato F.Madau P.Shen S.Vogelsberger M.2019-01-28T04:50:51Z2017-11-17T15:09:16ZCDS support team

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

cds-question@unistra.frhst-photometryvariable-starsglobular-star-clustersWe confirm that the object DDO 216-A1 is a substantial globular cluster at the center of Local Group galaxy DDO 216 (the Pegasus dwarf irregular), using Hubble Space Telescope ACS imaging. By fitting isochrones, we find the cluster metallicity [M/H]=-1.6+/-0.2, for reddening E(B-V)=0.16+/-0.02; the best-fit age is 12.3+/-0.8Gyr. There are ~30 RR Lyrae variables in the cluster; the magnitude of the fundamental mode pulsators gives a distance modulus of 24.77+/-0.08 --identical to the host galaxy. The ratio of overtone to fundamental mode variables and their mean periods make DDO 216-A1 an Oosterhoff Type I cluster. We find a central surface brightness of 20.85+/-0.17 F814W mag/arcsec^2^, a half-light radius of 3.1" (13.4pc), and an absolute magnitude M814=-7.90+/-0.16 (M/M_{sun}_~10^5^). King models fit to the cluster give the core radius and concentration index, r_c_=2.1"+/-0.9" and c=1.24+/-0.39. The cluster is an "extended" cluster somewhat typical of some dwarf galaxies and the outer halo of the Milky Way. The cluster is projected <~30pc south of the center of DDO 216, unusually central compared to most dwarf galaxy globular clusters. Analytical models of dynamical friction and tidal destruction suggest that it probably formed at a larger distance, up to ~1kpc, and migrated inward. DDO 216 has an unexceptional specific cluster frequency, S_N_=10. DDO 216 is the lowest-luminosity Local Group galaxy to host a 10^5^M_{sun}_ globular cluster and the only transition-type (dSph/dIrr) galaxy in the Local Group with a globular cluster.2017ApJ...837...54Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/837/54CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/hst : HST Archived Exposures Catalog (STScI, 2007)VII/195 : Globular Clusters in the Milky Way (Harris, 1996)J/MNRAS/345/747 : RR Lyrae in 4 Fornax globular clusters (Mackey+, 2003)J/ApJS/161/304 : Star clusters in the MW and satellites (McLaughlin+, 2005)J/A+A/442/85 : GC candidates in Low SB Galaxies (Sharina+, 2005)J/ApJ/699/1742 : LCID project. I. Cetus and Tucana variables (Bernard+, 2009)J/ApJ/697/1993 : Spitzer study of AGB stars. III. (Boyer+, 2009)J/MNRAS/396/1075 : GC in nearby dwarf galaxies. II (Georgiev+, 2009)J/MNRAS/392/879 : Globular clusters in nearby dwarf galaxies (Georgiev+, 2009)J/MNRAS/406/329 : Variable stars in M54 (Sollima+, 2010)J/AJ/142/187 : HST obs. of 7 Pop.II variable stars (Benedict+, 2011)J/AJ/142/199 : Sizes and luminosities of stellar systems (Brodie+, 2011)J/MNRAS/411/1536 : Spectroscopy of of IC4499 red giants (Hankey+, 2011)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/MNRAS/441/3570 : Nuclear star clusters in 228 spiral gal. (Georgiev+, 2014)J/MNRAS/439/1015 : Velocities of red giants in 7 LG dwarf gal. (Kirby+, 2014)J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)J/ApJ/812/158 : Leo P RR Lyrae candidates & cumulative SFH (McQuinn+, 2015)J/ApJ/829/26 : Variable stars in Andromeda XXV field. III. (Cusano+, 2016)J/MNRAS/457/2122 : Nuclear star clusters photometric masses (Georgiev+, 2016)J/ApJ/827/33 : PHAT. XVI. Star cluster masses and ages (Johnson+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/837/54https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/837/54http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/837/54https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/837/54https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/837/54http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/837/54GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/837/54/table1 (Variable stars in DDO216-A1)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/837/54/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/837/54/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/837/54/table1?GETtext/xml+votable180.050000true352.1513514.740097220.0055555555555555566/199902.3657755224268815e-19 4.369938604086476e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/837/54?format=asciidefaultJ/ApJ/837/54/table1Variable stars in DDO216-A1ID[16415/40802] Index number (1)meta.id;meta.mainintPer[0.3/1] Perioddtime.periodfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000[23] Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000[14] Degree of declination (J2000)pos.eq.dec;meta.mainXpixX pixel coordinatepixpos.cartesian.xfloatYpixY pixel coordinatepixpos.cartesian.yfloatgmag[25.3/26.4] Mean HST/ACS F475W (g) band magnitudemagphot.mag;em.opt.Bfloate_gmag[0.02/0.1] Uncertainty in F475Wmagmagstat.error;phot.mag;em.opt.BfloatImag[24.4/25.3] Mean HST/ACS F814W (I) band magnitudemagphot.mag;em.opt.Ifloate_Imag[0.02/0.05] Uncertainty in F814Wmagmagstat.error;phot.mag;em.opt.Ifloate_Per[0.01/0.2]? Uncertainty in Perdstat.errorfloatnullableTypeVariable typesrc.classchar