J/A+A/635/A152ivo://CDS.VizieR/J/A+A/635/A152doi:10.26093/cds/vizier.36350152CDSTaibi S.Battaglia G.Rejkuba M.Leaman R.Kacharov N.Iorio G.,Jablonka P.Zoccali M.2022-09-02T08:52:58Z2020-07-22T14:09:12ZCDS support team

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

cds-question@unistra.frgalaxiesphotometryradial-velocitychemical-abundancesIsolated local group (LG) dwarf galaxies have evolved most or all of their life unaffected by interactions with the large LG spirals and therefore offer the opportunity to learn about the intrinsic characteristics of this class of objects. Our aim is to explore the internal kinematic and metallicity properties of one of the three isolated LG early-type dwarf galaxies, the Tucana dwarf spheroidal. This is an intriguing system, as it has been found in the literature to have an internal rotation of up to 16km/s, a much higher velocity dispersion than dwarf spheroidals of similar luminosity, and a possible exception to the too-big-too-fail problem. We present the results of a new spectroscopic dataset that we procured from the Very Large Telescope (VLT) taken with the FORS2 instrument in the region of the Ca II triplet for 50 candidate red giant branch stars in the direction of the Tucana dwarf spheroidal. These yielded line-of-sight (l.o.s.) velocity and metallicity ([Fe/H]) measurements of 39 effective members that double the number of Tucana's stars with such measurements. In addition, we re-reduce and include in our analysis the other two spectroscopic datasets presented in the literature, the VLT/FORS2 sample by Fraternali et al. (2009A&A...499..121F), and the VLT/FLAMES one from Gregory et al. (2019MNRAS.485.2010G). Across the various datasets analyzed, we consistently measure a l.o.s. systemic velocity of 180+/-1.3km/s and find that a dispersion-only model is moderately favored over models that also account for internal rotation. Our best estimate of the internal l.o.s. velocity dispersion is 6.2_-1.3_^+1.6^km/s, much smaller than the values reported in the literature and in line with similarly luminous dwarf spheroidals; this is consistent with NFW halos of circular velocities <30km/s. Therefore, Tucana does not appear to be an exception to the too-big-to-fail problem, nor does it appear to reside in a dark matter halo much more massive than those of its siblings. As for the metallicity properties, we do not find anything unusual; there are hints of the presence of a metallicity gradient, but more data are needed to pinpoint its presence.2020A&A...635A.152Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/635/A152CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/635/A152https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/635/A152http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/635/A152https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/635/A152https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/635/A152http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/635/A152GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/635/A152/tablec1 (Properties of observed P91-FORS2 dataset in the Tucana dSph)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/635/A152/tablec1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/635/A152/tablec1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/635/A152/tablec1?GETtext/xml+votable180.050000true340.4913-64.418960.005555555555555556Cone search capability for table J/A+A/635/A152/tablec2 (Properties of observed P69-FORS2 dataset in the Tucana dSph)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/635/A152/tablec2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/635/A152/tablec2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/635/A152/tablec2?GETtext/xml+votable180.050000true340.4472-64.422090.005555555555555556Cone search capability for table J/A+A/635/A152/tablec3 (Properties of observed FLAMES/GIRAFFE dataset in the Tucana dSph)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/635/A152/tablec3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/635/A152/tablec3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/635/A152/tablec3?GETtext/xml+votable180.050000true340.34104-64.36677810.0055555555555555566/45423https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/635/A152?format=asciidefaultJ/A+A/635/A152/tablec1Properties of observed P91-FORS2 dataset in the Tucana dSphSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintField[0/1]? Field, 0 for Tuc0 and 1 for Tuc1meta.id;obs.fieldintnullableSlitSlit number within the field (1)meta.idintn_Slit[R] R for repeated measurements (2)meta.notecharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainVmagV magnitude from VLT/FORS2 photometric catalogmagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on V magnitudemagstat.error;phot.magfloatImagI magnitude from VLT/FORS2 photometric catalogmagphot.mag;em.opt.Ifloate_Imagrms uncertainty on I magnitudemagstat.error;phot.magfloatHV? LOS heliocentric velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatnullablee_HV? rms uncertainty on heliocentric velocitykm/sstat.errorfloatnullable[Fe/H]? Metallicityphys.abund.Zfloatnullablee_[Fe/H]? rms uncertainty on metallicitystat.error;phys.abund.FefloatnullableS/NSignal-to-noise ratio (the conversion factor to {AA}^-1^ is 1.09)pixel**-1stat.snrfloatnP[Ph ] Ph for non-members (G1)meta.codecharP1? Probability of membership obtained using the P91 dataset alonestat.probabilityfloatnullableP2? Probability of membership obtained using the P91 dataset combining with the P69stat.probabilityfloatnullableP3? Probability of membership obtained using the P91 dataset combining with the P69 and further adding the FLAMES datameta.datasetfloatnullableJ/A+A/635/A152/tablec2Properties of observed P69-FORS2 dataset in the Tucana dSphSimbadNameSimbad column added by the CDSmeta.idcharnullableSlitSlit number (1)meta.idintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_Slit[a,b ] Note on Slit (2)meta.notecharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainVmag? V magnitude from VLT/FORS2 photometric catalogmagphot.mag;em.opt.Vfloatnullablee_Vmag? rms uncertainty on Vmagmagstat.error;phot.magfloatnullableImag? I magnitude from VLT/FORS2 photometric catalogmagphot.mag;em.opt.Ifloatnullablee_Imag? rms uncertainty on Imagmagstat.error;phot.magfloatnullableHVLOS heliocentric velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_HVrms uncertainty on HVkm/sstat.errorfloat[Fe/H]? Metallicityphys.abund.Zfloatnullablee_[Fe/H]? rms uncertainty on [Fe/H]stat.error;phys.abund.FefloatnullableS/NSignal-to-noise ratio (the conversion factor to {AA}^-1^ is 1.08)pixel**-1stat.snrfloatnP[Ph ] Ph for non-members (G1)meta.codecharP1? Probability of membership obtained using the P91 dataset alonestat.probabilityfloatnullableP2? Probability of membership obtained using the P91 dataset combining with the P69stat.probabilityfloatnullableP3? Probability of membership obtained using the P91 dataset combining with the P69 and further adding the FLAMES datameta.datasetfloatnullableJ/A+A/635/A152/tablec3Properties of observed FLAMES/GIRAFFE dataset in the Tucana dSphSimbadNameSimbad column added by the CDSmeta.idcharnullableVmagV magnitude transformed from DES photometric catalogmagphot.mag;em.opt.VfloatImagI magnitude transformed from DES photometric catalogmagphot.mag;em.opt.IfloatHV? LOS heliocentric velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatnullablee_HV? rms uncertainty on HVkm/sstat.errorfloatnullableS/NSignal-to-noise ratio (the conversion factor to {AA}^-1^ is 2.24)pixel**-1stat.snrfloatnP[Ph ] Ph for non-members (G1)meta.codecharP1? Probability of membership obtained using the FLAMES dataset alonestat.probabilityfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObjectObject-ID from fits headermeta.idintFiberFiber-ID used through textmeta.noteintRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainNote[a] a: in common with the FORS2 datasetmeta.notecharP2? Probability of membership obtained using the FLAMES dataset combining with the FORS2 datameta.datasetfloatnullable