J/ApJ/819/53ivo://CDS.VizieR/J/ApJ/819/53doi:10.26093/cds/vizier.18190053CDSWalker M.G.Mateo M.Olszewski E.W.Koposov S.Belokurov V.Jethwa P.,Nidever D.L.Bonnivard V.Bailey III J.I.Bell E.F.Loebman S.R.2018-01-08T07:01:55Z2016-06-17T14:39:31ZCDS support team

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

cds-question@unistra.frgalaxiesspectroscopymetallicityinfrared-photometryvisible-astronomybroad-band-photometryWe present results from spectroscopic observations with the Michigan/Magellan Fiber System (M2FS) of 147 stellar targets along the line of sight to the newly discovered "ultrafaint" stellar systems Tucana 2 (Tuc 2) and Grus 1 (Gru 1). Based on simultaneous estimates of line of sight velocity and stellar-atmospheric parameters, we identify 8 and 7 stars as probable members of Tuc 2 and and Gru 1, respectively. Our sample for Tuc 2 is sufficient to resolve an internal velocity dispersion of 8.6^+4.4^_-2.7_km/s about a mean of -129.1+/-3.5km/s (solar rest frame), and to estimate a mean metallicity of [Fe/H]=-2.23^+0.18^_-0.12_. These results place Tuc 2 on chemodynamical scaling relations followed by dwarf galaxies, suggesting a dominant dark matter component with dynamical mass 2.7^+3.1^_-1.3_x10^6^M_{sun}_ enclosed within the central ~160pc, and dynamical mass-to-light ratio 1913^+2234^_-950_M_{sun}_/L_{nu},{sun}_. For Gru 1 we estimate a mean velocity of -140.5^+2.4^_-1.6_km/s and a mean metallicity of [Fe/H]=-1.42^+0.55^_-0.42_ but our sample does not resolve Gru 1's velocity dispersion. The radial coordinates of Tuc 2 and Gru 1 in Galactic phase space suggest that their orbits are among the most energetic within a distance of <~300pc. Moreover, their proximity to each other in this space arises naturally if both objects are trailing the Large Magellanic Cloud.2016ApJ...819...53Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/819/53CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/808/108 : M2FS stellar spectroscopy of Reticulum 2 (Walker+, 2015)J/MNRAS/448/2717 : Bayesian analysis of resolved spectra (Walker+, 2015)J/ApJ/801/74 : Dark matter profiles in dwarf galaxies (Geringer-Sameth+, 2015)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/819/53https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/819/53http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/819/53https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/819/53https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/819/53http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/819/53GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/819/53/table1 (Michigan/Magellan Fiber System (M2FS) stellar spectroscopy of Tucana 2 and Grus 1)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/819/53/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/819/53/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/819/53/table1?GETtext/xml+votable180.050000true342.9685-58.56950.0055555555555555566/46126 46212 46279 462902.85864675833786e-19 4.653515163505597e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/819/53?format=asciiInfraredOpticaldefaultJ/ApJ/819/53/table1Michigan/Magellan Fiber System (M2FS) stellar spectroscopy of Tucana 2 and Grus 1recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalDwarf galaxy ("Gru1" or "Tuc2")src.class.starGalaxycharSeq[1/137] Target Identifier (1)meta.id;meta.mainintRAJ2000[22] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[49/58] Degree of Declination (J2000)pos.eq.dec;meta.maingmag[17/22.5] g band AB magnitude (1)magphot.mag;em.opt.Bfloatrmag[15.8/22.3] r band AB magnitude (1)magphot.mag;em.opt.RfloatHJDHeliocentric Julian date; HJD-2450000dtime.epochdoubleS/N[-0.4/32] Median Signal/Noise Ratio per pixelem.wl.central;stat.medianfloatVlos[-264/469] Line-of-Sight velocity, solar rest framekm/sphys.velocfloate_Vlos[0.3/328] Uncertainty in Vloskm/sstat.errorfloatSVlos[-109/33] Skewness in Vlosstat.fit.paramfloatKVlos[1.6/13935] Kurtosis in Vlosstat.fit.paramfloatTeff[4025/7921] Effective TemperatureKphys.temperature.effectiveinte_Teff[21/991] Uncertainty in TeffKstat.error;phys.temperature.effectiveintSTeff[-1.7/1.6] Skewness in Teffstat.fit.paramfloatKTeff[2/7] Kurtosis in Teffstat.fit.paramfloatlogg[0.7/5.2] Log surface gravity, cgs unitslog(cm.s**-2)meta.unit;phys.gravityfloate_logg[0.1/1.5] Uncertainty in logglog(cm.s**-2)stat.errorfloatSlogg[-3/3] Skewness in loggstat.fit.paramfloatKlogg[1.8/15] Kurtosis in loggstat.fit.paramfloat[Fe/H][-3.9/0.9] Metallicitylog(Sun)phys.abund.Zfloate_[Fe/H][0.05/1.9] Uncertainty in [Fe/H]log(Sun)stat.error;phys.abund.FefloatS[Fe/H][-3.8/0.6] Skewness in [Fe/H]stat.fit.paramfloatK[Fe/H][1.6/20.4] Kurtosis in [Fe/H]stat.fit.paramfloatPMm[0/1] Probability of membership (2)stat.probabilityfloate_PMm[0/0.3] Uncertainty in PMmstat.errorfloatChSpectrograph channel (B:Blue, R:Red)instr.setupcharMdSpectrograph mode (H:HiRes, M:MedRes)instr.setupcharSimbadSimbad column added by the CDSmeta.ref.urlchar