J/ApJ/883/11ivo://CDS.VizieR/J/ApJ/883/11doi:10.26093/cds/vizier.18830011CDSFu S.W.Simon J.D.Jara A.G.A.2022-09-02T09:27:51Z2021-03-16T12:33:14ZCDS support team

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

cds-question@unistra.frgalaxiesspectroscopyinfrared-astronomyvisible-astronomysurveysradial-velocitymetallicityline-intensitiesWe investigate the possibility that the dwarf galaxies Crater II and Hercules have previously been tidally stripped by the Milky Way. We present Magellan/IMACS spectra of candidate member stars in both objects. We identify 37 members of Crater II, 25 of which have velocity measurements in the literature, and we classify three stars within that subset as possible binaries. We find that including or removing these binary candidates does not change the derived velocity dispersion of Crater II. Excluding the binary candidates, we measure a velocity dispersion of {sigma}_Vlos_=2.7_-0.4_^+0.5^km/s, corresponding to M/L=47_-13_^+17^M_{sun}_/L_{sun}_. We measure a mean metallicity of [Fe/H]=-1.95_-0.05_^+0.06^, with a dispersion of {sigma}_[Fe/H]_=0.18_-0.08_^+0.06^. Our velocity dispersion and metallicity measurements agree with previous measurements for Crater II, and confirm that the galaxy resides in a kinematically cold dark-matter halo. We also search for spectroscopic members stripped from Hercules in the possible extratidal stellar overdensities surrounding the dwarf. For both galaxies, we calculate proper motions using Gaia DR2 astrometry, and use their full 6D phase space information to evaluate the probability that their orbits approach sufficiently close to the Milky Way to experience tidal stripping. Given the available kinematic data, we find a probability of ~40% that Hercules has suffered tidal stripping. The proper motion of Crater II makes it almost certain to be stripped.2019ApJ...883...11Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/883/11CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006)J/ApJ/704/898 : Photometry of the Hercules dwarf galaxy (Sand+, 2009)J/ApJ/756/121 : Variable stars in Her dwarf galaxy (Musella+, 2012)J/ApJ/752/45 : SPLASH: Stellar spec. of M31 satellites (Tollerud+, 2012)J/MNRAS/434/1681 : Extremely metal-poor stars CaII triplet (Carrera+, 2013)J/ApJ/768/172 : Kinematic of red giant in M31 dSphs (Collins+, 2013)J/A+A/570/A61 : PM-selected stars of Hercules galaxy (Fabrizio+, 2014)J/ApJ/808/95 : Spectroscopy of Reticulum II (Simon+, 2015)J/ApJ/833/167 : PAndAS view of Andromeda satellites. II. (Martin+, 2016)J/ApJ/838/11 : Member stars in the MW satellite Tucana III (Simon+, 2017)J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)J/ApJ/861/23 : RR Lyrae stars in the Crater II dwarf galaxy (Joo+, 2018)J/ApJ/866/22 : Spectroscopic analysis of Tuc III stream (Li+, 2018)J/A+A/620/A155 : Gaia proper motions of 7 UFD galaxies (Massari+, 2018)J/ApJ/863/25 : Deep Megacam obs. of 4 MW satellites (Mutlu-Pakdil+, 2018)J/ApJ/863/89 : Gaia DR2 PMs in ultra-faint MW satellites (Simon, 2018)J/AJ/156/257 : RGB stars spectroscopy in Draco & Ursa Minor (Spencer+, 2018)J/A+A/616/A165 : K' images of star-forming dwarf galaxies (Vaduvescu+, 2018)J/ApJ/875/77 : PMs of MW satellites with Gaia & DES (Pace+, 2019)http://www.sdss.org/ : SDSS home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/883/11https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/883/11http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/883/11https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/883/11https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/883/11http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/883/11GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/883/11/table2 (Spectroscopic measurements for Crater II and Hercules targets -- from erratum published in 2021, ApJ, 923, 281)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/883/11/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/883/11/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/883/11/table2?GETtext/xml+votable180.050000true177.05862-18.366230.0055555555555555566/25180-25181 31692 316942.85864675833786e-19 4.653515163505597e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/883/11?format=asciiOpticalInfrareddefaultJ/ApJ/883/11/table2Spectroscopic measurements for Crater II and Hercules targets -- from erratum published in 2021, ApJ, 923, 281SimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalDwarf galaxy namemeta.id.parentcharobjIDUnique object identifier in source catalog (PSO JHHMMSS.ss+DDMMSS.s or SDSS JHHMMSS.ss+DDMMSS.s)meta.id;meta.maincharMJD[57567.0/58203.3]? Modified Julian Date of spectrum (JD-2400000.5) (2)dtime.epochfloatnullableRAJ2000[177/247.6] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-18.7/13] Declination (J2000)degpos.eq.dec;meta.maingmag[13.3/23.2] g-band AB magnitude in filter system (PS1 or SDSS) (1)magphot.mag;em.opt.Bfloatrmag[12.2/21.4] r-band AB magnitude in filter system (PS1 or SDSS) (1)magphot.mag;em.opt.RfloatSourceSource catalog and filter system (PS1 or SDSS) (1)meta.idcharSN[5/496.5] Signal-to-Noise ratio per pixelpixel**-1stat.snr;instr.pixelfloatHRV[-487/400] Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_HRV[1/6.4] Uncertainty in HRVkm/sstat.errorfloatEWCa[1.3/7.3]? Equivalent Width, five-parameter calcium triplet0.1nmspect.line.eqWidthfloatnullablee_EWCa[0/1]? Uncertainty in EWCa0.1nmstat.errorfloatnullable[Fe/H][-2.82/-1.74]? Metallicity, [Fe/H]phys.abund.Zfloatnullablee_[Fe/H][0.15/0.53]? Uncertainty in [Fe/H]stat.error;phys.abund.FefloatnullableRegRegion of Hercules overdensity (3)obs.fieldcharMm[0/1]? Membership in dwarf galaxy (4)meta.code.memberintnullablePS1Display data from PS1 (II/349) within 0.5"meta.ref.urlcharSloanDisplay the online SDSS-DR14 data for the nearest objectmeta.ref.urlchar