J/ApJ/778/L13ivo://CDS.VizieR/J/ApJ/778/L13doi:10.26093/cds/vizier.17789013CDSLee Y.-W.Han S.-I.Joo S.-J.Jang S.Na C.Okamoto S.Arimoto N.,Lim D.Kim H.-S.Yoon S.-J.2017-06-27T06:38:51Z2015-06-08T15:16:30ZCDS support team

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

cds-question@unistra.frvisible-astronomynarrow-band-photometryRecent spectroscopic observations of the outer halo globular cluster (GC) NGC 2419 show that it is unique among GCs, in terms of chemical abundance patterns, and some suggest that it was originated in the nucleus of a dwarf galaxy. Here we show, from the Subaru narrowband photometry employing a calcium filter, that the red giant branch (RGB) of this GC is split into two distinct subpopulations. Comparison with spectroscopy has confirmed that the redder RGB stars in the hk[=(Ca-b)-(b-y)] index are enhanced in [Ca/H] by ~0.2dex compared to the bluer RGB stars. Our population model further indicates that the calcium-rich second generation stars are also enhanced in helium abundance by a large amount ({Delta}Y=0.19). Our photometry, together with the results for other massive GCs (e.g., {omega} Cen, M22, and NGC 1851), suggests that the discrete distribution of RGB stars in the hk index might be a universal characteristic of this growing group of peculiar GCs. The planned narrowband calcium photometry for the Local Group dwarf galaxies would help to establish an empirical connection between these GCs and the primordial building blocks in the hierarchical merging paradigm of galaxy formation.2013ApJ...778L..13Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/778/L13CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/subaru : Log of Subaru Prime Focus Camera Exposures (ADAC NAOJ, 2007)J/MNRAS/431/1995 : Deep uVI photometry of NGC2419 (Beccari+, 2013)J/ApJ/769/40 : Potassium abundance in red giants of GCs (Carretta+, 2013)J/ApJ/760/86 : Equivalent widths for 13 NGC2419 RGB stars (Cohen+, 2012)J/A+A/541/A15 : Abundances of M22 subgiants (Marino+, 2012)J/ApJ/705/1481 : Spectroscopy of stars in 6 globular clusters (Da Costa+, 2009)J/ApJ/681/311 : Blue stragglers in NGC 2419 (Dalessandro+, 2008)J/AJ/131/461 : Stromgren photometry of NGC 2420 (Anthony-Twarog+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/778/L13https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/778/L13http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/778/L13https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/778/L13https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/778/L13http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/778/L13GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/778/L13/fig1cNew Yonsei Ca filter transmission employed at Subaru (figure 1c)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength in Angstroms (1)0.1nmem.wlintTransTransmission percentage (1)%phys.transmission;instr.filterdouble