J/MNRAS/491/356ivo://CDS.VizieR/J/MNRAS/491/356doi:10.26093/cds/vizier.74910356CDSLongeard N.Martin N.Starkenburg E.Ibata R.A.Collins M.L.M.,Laevens B.P.M.Mackey D.Rich R.M.Aguado D.S.Arentsen A.,Jablonka P.Gonzalez Hernandez J.I.Navarro J.F.Sanchez-Janssen R.2024-08-20T20:14:44Z2023-03-29T14:18:26ZCDS support team

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

cds-question@unistra.frgalaxiesmetallicityradial-velocityproper-motionsphotometryspectroscopyvisible-astronomyWe present an extensive study of the Sagittarius II (Sgr II) stellar system using MegaCam g and i photometry, narrow-band, metallicity-sensitive calcium H&K doublet photometry and Keck II/DEIMOS multiobject spectroscopy. We derive and refine the Sgr II structural and stellar properties inferred at the time of its discovery. The colour-magnitude diagram implies Sgr II is old (12.0+/-0.5Gyr) and metal poor. The CaHK photometry confirms the metal-poor nature of the satellite ([Fe/H]_CaHK_=-2.32+/-0.04dex) and suggests that Sgr II hosts more than one single stellar population ({sigma}_[Fe/H]_^CaHK^=0.11^+0.05^_-0.03_dex). Using the Ca infrared triplet measured from our highest signal-to-noise spectra, we confirm the metallicity and dispersion inferred from the Pristine photometric metallicities ([Fe/H]_spectro_=-2.23+/-0.05dex, {sigma}_[Fe/H]_^spectro^=0.10^+0.06^_-0.04_dex). The velocity dispersion of the system is found to be {sigma}_v_=2.7^+1.3^_-1.0_km/s after excluding two potential binary stars. Sgr II's metallicity and absolute magnitude (M_V_=-5.7+/-0.1mag) place the system on the luminosity-metallicity relation of the Milky Way dwarf galaxies despite its small size. The low but resolved metallicity and velocity dispersions paint the picture of a slightly dark-matter-dominated satellite (M/L=23.0^+32.8^_-23.0_M_{sun}_/L_{sun}_). Furthermore, using the Gaia Data Release 2, we constrain the orbit of the satellite and find an apocentre of 118.4^+28.4^_-23.7_kpc and a pericentre of 54.8^+3.3^_-6.1_kpc. The orbit of Sgr II is consistent with the trailing arm of the Sgr stream and indicates that it is possibly a satellite of the Sgr dSph that was tidally stripped from the dwarf's influence.2020MNRAS.491..356Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/491/356CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/491/356https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/491/356http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/491/356https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/491/356https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/491/356http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/491/356GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/491/356/table2 (Properties of our spectroscopic sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/491/356/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/491/356/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/491/356/table2?GETtext/xml+votable180.050000true298.20599-21.98790.005555555555555556Cone search capability for table J/MNRAS/491/356/table3 (Velocities and individual metallicities for all stars observed more than once, per mask)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/491/356/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/491/356/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/491/356/table3?GETtext/xml+votable180.050000true298.18001-22.071750.0055555555555555566/48771 48774 48777 48780https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/491/356?format=asciiOpticaldefaultJ/MNRAS/491/356/table2Properties of our spectroscopic samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintf_[Fe/H]ph[*] Flag on [Fe/H]ph (2)meta.codecharSimbadNameSimbad column added by the CDSmeta.idcharnullableRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.maing0magDereddened g-band magnitudemagphot.mag;em.opt.Bfloate_g0magError on g0magmagstat.error;phot.magfloati0magDereddened i-band magnitudemagphot.mag;em.opt.Ifloate_i0magError on i0magmagstat.error;phot.magfloatCaHK0magDereddened CaHK-band magnitudemagphot.magfloate_CaHK0magError on CaHK0magmagstat.error;phot.magfloatRVRadial velocitykm/sphys.veloc;pos.heliocentricfloate_RVError on RV (G1)km/sstat.errorfloatpmRA? Proper motion in right ascensionmas/yrpos.pm;pos.eq.rafloatnullablee_pmRA? Error on pmRAmas/yrstat.error;pos.pm;pos.eq.rafloatnullablepmDE? Proper motion in declinationmas/yrpos.pm;pos.eq.decfloatnullablee_pmDE? Error on pmDEmas/yrstat.error;pos.pm;pos.eq.decfloatnullableS/NSignal to noise ratiostat.snrfloat[Fe/H]ph? Photometric metallicity obtained by combining the CaHK_0_ magnitude with the broad-band g_0_ and i_0_ photometry (1)phys.abund.Fefloatnullablee_[Fe/H]ph? Error on [Fe/H]phstat.error;phys.abund.Fefloatnullable[Fe/H]sp? Spectroscopic metallicity (G2)phys.abund.Fefloatnullablee_[Fe/H]sp? Error on [Fe/H]spstat.error;phys.abund.FefloatnullablePmemProbability membershipstat.probabilityfloatMember[Y/N/HB] Membership (3)meta.code.membercharJ/MNRAS/491/356/table3Velocities and individual metallicities for all stars observed more than once, per maskrecnoRecord 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.mainMaskMask used for observation (1)instr.setupcharRVRadial velocitykm/sphys.veloc;pos.heliocentricfloate_RVError on RV (G1)km/sstat.errorfloat[Fe/H]sp? Spectroscopic redshift (G2)phys.abund.Fefloatnullablee_[Fe/H]sp? Error on [Fe/H]spstat.error;phys.abund.Fefloatnullable