J/MNRAS/458/L59ivo://CDS.VizieR/J/MNRAS/458/L59doi:10.26093/cds/vizier.74589059CDSMartin N.F.Geha M.Ibata R.A.Collins M.L.M.Laevens B.P.M.,Bell E.F.Rix H.-W.Ferguson A.M.N.Chambers K.C.Wainscoat R.J.,Waters C.2024-08-16T20:16:36Z2018-12-12T09:13:30ZCDS support team

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

cds-question@unistra.frgalaxiesvisible-astronomysloan-photometryradial-velocityWe present the first spectroscopic analysis of the faint and compact stellar system Draco II (Dra II, M_V_=-2.9+/-0.8,r_h_=19^+8^_-6_pc), recently discovered in the Panoramic Survey Telescope and Rapid Response System 1 3{PI} survey. The observations, conducted with DEIMOS on the Keck II telescope, establish some of its basic characteristics: the velocity data reveal a narrow peak with nine member stars at a systemic heliocentric velocity <v_r_>=-347.6^+1.7^_-1.8_km/s, thereby confirming Dra II is a satellite of the Milky Way; we infer a velocity dispersion with {sigma}_vr_=2.9+/-2.1km/s (<8.4km/s at the 95 per cent confidence level), which implie log_10_(M_1/2_)-5.5^+0.4^_-0.6_ and log_10_((M/L_)1/2_)=2.7^+0.5^_-0.8_, in Solar units; furthermore, very weak calcium triplet lines in the spectra of the high signal-to-noise member stars imply [Fe/H]<-2.1, whilst variations in the line strengths of two stars with similar colours and magnitudes suggest a metallicity spread in Dra II. These new data cannot clearly discriminate whether Draco II is a star cluster or amongst the faintest, most compact, and closest dwarf galaxies. However, the sum of the three - individually inconclusive - pieces of evidence presented here seems to favour the dwarf galaxy interpretation.2016MNRAS.458L..59Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/458/L59CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/458/L59https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/458/L59http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/458/L59https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/458/L59https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/458/L59http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/458/L59GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/458/L59/table1 (Properties of observed stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/458/L59/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/458/L59/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/458/L59/table1?GETtext/xml+votable180.050000true238.345367464.57397460.0055555555555555566/11655https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/458/L59?format=asciiOpticaldefaultJ/MNRAS/458/L59/table1Properties of observed starsiP1magPS1 i magnitudemagphot.mag;em.opt.IfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqSequential numbermeta.recordintRA_ICRSRight ascension (ICRS)degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS)degpos.eq.dec;meta.maingP1magPS1 g magnitudemagphot.mag;em.opt.Bfloate_gP1magrms uncertainty on gP1magmagstat.error;phot.magfloate_iP1magrms uncertainty on iP1magmagstat.error;phot.magfloatMemb[Y/N] Membermeta.code.membercharRVRadial velocitykm/sphys.veloc;pos.heliocentricfloate_RVrms uncertainty on RVkm/sstat.errorfloatS/NSignal-to-noise ratiostat.snrfloat[Fe/H]? Tentative [Fe/H]phys.abund.FefloatnullableE_[Fe/H]? Error on [Fe/H] (upper value)stat.error;stat.maxfloatnullablee_[Fe/H]? Error on [Fe/H] (lower value)stat.error;phys.abund.FefloatnullableSimbadSimbad column added by the CDSmeta.ref.urlchar