J/ApJ/838/83ivo://CDS.VizieR/J/ApJ/838/83doi:10.26093/cds/vizier.18380083CDSKirby E.N.Cohen J.G.Simon J.D.Guhathakurta P.Thygesen A.O.,Duggan G.E.2018-03-12T08:40:32Z2017-12-06T15:39:23ZCDS support team

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

cds-question@unistra.frchemical-abundancesradial-velocitygalaxy-kinematicsline-intensitiesvisible-astronomysloan-photometrygalaxiesAmong the Milky Way satellites discovered in the past three years, Triangulum II has presented the most difficulty in revealing its dynamical status. Kirby+ (2015ApJ...814L...7K) identified it as the most dark-matter-dominated galaxy known, with a mass-to-light ratio within the half-light radius of 3600_-2100_^+3500^M_{sun}_/L_{sun}_. On the other hand, Martin+ (2016ApJ...818...40M) measured an outer velocity dispersion that is 3.5+/-2.1 times larger than the central velocity dispersion, suggesting that the system might not be in equilibrium. From new multi-epoch Keck/DEIMOS measurements of 13 member stars in Triangulum II, we constrain the velocity dispersion to be {sigma}_v_<3.4km/s (90%C.L.). Our previous measurement of {sigma}_v_, based on six stars, was inflated by the presence of a binary star with variable radial velocity. We find no evidence that the velocity dispersion increases with radius. The stars display a wide range of metallicities, indicating that Triangulum II retained supernova ejecta and therefore possesses, or once possessed, a massive dark matter halo. However, the detection of a metallicity dispersion hinges on the membership of the two most metal-rich stars. The stellar mass is lower than galaxies of similar mean stellar metallicity, which might indicate that Triangulum II is either a star cluster or a tidally stripped dwarf galaxy. Detailed abundances of one star show heavily depressed neutron-capture abundances, similar to stars in most other ultra-faint dwarf galaxies but unlike stars in globular clusters.2017ApJ...838...83Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/838/83CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/287/927 : Abundances for lines of n-capture in 19 stars (Gratton+ 1994)J/AJ/120/1841 : Abundances & Kinematics of Halo & Disk Stars (Fulbright 2000)J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006)J/ApJ/663/960 : Radial velocities of Leo I stars (Sohn+, 2007)J/ApJ/682/1217 : Abundances in red giants in 7 globular clusters (Kirby+, 2008)J/ApJ/692/1464 : Spectroscopy of Segue 1 (Geha+, 2009)J/ApJ/705/328 : Abundance measurements in Sculptor dSph (Kirby+, 2009)J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010)J/ApJS/191/352 : Abundances in stars of MW dwarf satellites (Kirby+, 2010)J/ApJ/740/60 : EWs for NGC2419 and NGC7099 RGB stars (Cohen+, 2011)J/ApJ/736/146 : Radial velocities of stars in Bootes I (Koposov+, 2011)J/ApJ/733/46 : Velocity measurements in Segue 1 (Simon+, 2011)J/ApJ/760/86 : Equivalent widths for 13 NGC2419 RGB stars (Cohen+, 2012)J/AJ/144/168 : Spectroscopy of Scl 1019417 and UMi 20103 (Kirby+, 2012)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)J/ApJ/770/16 : Spectroscopic members of Segue 2 galaxy (Kirby+, 2013)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/ApJ/767/134 : Abundances of red giant stars in UFD galaxies (Vargas+, 2013)J/ApJ/786/74 : EW measurements of 6 Segue 1 red giants (Frebel+, 2014)J/ApJ/801/125 : Carbon in red giants in GCs and dSph galaxies (Kirby+, 2015)J/ApJ/808/95 : Spectroscopy of Reticulum II (Simon+, 2015)J/ApJ/830/93 : Ret II brightest red giant members abundances (Ji+, 2016)J/ApJ/817/41 : Abundances of 4 metal-poor red giants in BooII (Ji+, 2016)J/ApJ/819/135 : Lithium-rich giants in globular clusters (Kirby+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/838/83https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/838/83http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/838/83https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/838/83https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/838/83http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/838/83GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/838/83/table2 (Radial velocities)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/838/83/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/838/83/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/838/83/table2?GETtext/xml+votable180.050000true33.30287536.14705560.0055555555555555566/2341 2352https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/838/83?format=asciiOpticaldefaultJ/ApJ/838/83/table2Radial velocitiesSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[KCS2015][45/177]? Identifier from Kirby+ (2015ApJ...814L...7K)meta.id;meta.mainintnullable[MIC2016][1/50]? Identifier from Martin+ (2016ApJ...818...40M)meta.idintnullablef_[MIC2016][a,h ] Flag(s) on Star (1)meta.codecharRAJ2000[2] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[36] Degree of Declination (J2000)pos.eq.dec;meta.mainRad[0.1/8.3] Radiusarcminphys.angSizefloatgP1mag[17/22] Pan-STARRS-1 g mag photometry (2)magphot.mag;em.opt.Bfloate_gP1mag[0/0.2] Uncertainty for gP1magmagstat.error;phot.magfloatiP1mag[16.3/21.7] Pan-STARRS-1 i mag photometry (2)magphot.mag;em.opt.Ifloate_iP1mag[0/0.2] Uncertainty for iP1magmagstat.error;phot.magfloatMasks[ b-g] Slit Mask identifier(s) (3)meta.id;instr.setupcharS/N[14/220] Signal-to-noise ratio in {AA}^-1^ (4)stat.snrfloatHRV[-388/11]? Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatnullablee_HRV[1.5/18]? Uncertainty in HRVkm/sstat.errorfloatnullablesigma[0.1/3]? Velocity dispersion {sigma}({nu})km/sphys.veloc.dispersionfloatnullableMmMember status (Y: 13 sources; N: 20 sources)meta.code.membercharf_Mm[b] Flag on M16 25 (5)meta.codecharEWDisplay the EWs for this star (table 5)meta.ref.urlcharADisplay the chemical abundances for this star (table 4)meta.ref.urlcharJ/ApJ/838/83/table4Chemical abundancesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[KCS2015][65/128]? Identification number from Kirby+ (2015ApJ...814L...7K)meta.id;meta.mainintnullable[MIC2016][20/46]? Identification number from Martin+ (2016ApJ...818...40M)meta.idintnullableTeff[4917/5635] Effective temperatureKphys.temperature.effectiveintlogg[1.8/3.5] Log surface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H]CaT[-3.2/-0.9] Metallicity from the Ca tripletphys.abund.Fefloate_[Fe/H]CaT[0.02/0.2] [Fe/H]CaT uncertaintystat.error;phys.abund.Fefloat[Fe/H][-3/-1.4] [Fe/H] abundancephys.abund.Fefloate_[Fe/H][0.1/0.3] [Fe/H] uncertaintystat.error;phys.abund.Fefloat[Mg/Fe][0.2/1.1]? [Mg/Fe] abundancephys.abundfloatnullablee_[Mg/Fe][0.2/0.9]? [Mg/Fe] uncertaintystat.error;phys.abundfloatnullable[Si/Fe][-0.09/0.6]? [Si/Fe] abundancephys.abundfloatnullablee_[Si/Fe][0.1/0.5]? [Si/Fe] uncertaintystat.error;phys.abundfloatnullable[Ca/Fe][-0.4/0.5] [Ca/Fe] abundancephys.abundfloate_[Ca/Fe][0.1/0.9] [Ca/Fe] uncertaintystat.error;phys.abundfloat[Ti/Fe][-0.8/1]? [Ti/Fe] abundancephys.abundfloatnullablee_[Ti/Fe][0.1/0.8]? [Ti/Fe] uncertaintystat.error;phys.abundfloatnullable[a/Fe][-0.5/0.5] [{alpha}/Fe] abundancephys.abundfloate_[a/Fe][0.1/0.36] [a/Fe] uncertaintystat.error;phys.abundfloatJ/ApJ/838/83/table5*Line list with equivalent widths of [MIC2016] 40; from erratum published in 2017, ApJ, 839, 135IonIonphys.atmol.ionStagecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlamAir[3949.9/7699] Wavelength in air, in {AA} units (1)0.1nmem.wldoubleExPot[0/5.7] Excitation potentialeVphys.atmol.excitationfloatloggf[-9.8/0.7] Logarithm of oscillator strength (2)phys.atmol.oscStrengthfloatl_EWUpper limit flag on EWmeta.code.error;spect.line.eqWidthcharEW[4/287] Equivalent width0.1pmspect.line.eqWidthfloatl_epsUpper limit flag on epsmeta.code.errorchareps[-3.2/6.8] Abundance derived from this line, unitless relative to Sunlog(Sun)phys.abundfloat