J/MNRAS/514/1706ivo://CDS.VizieR/J/MNRAS/514/1706doi:10.26093/cds/vizier/bg-g2-1naCDSButtry R.Pace A.B.Koposov S.E.Walker M.G.Caldwell N.Kirby E.N.,Martin N.F.Mateo M.Olszewski E.W.Starkenburg E.Badenes C.,Daher C.M.2026-08-03T07:31:26Z2025-06-06T11:11:19ZCDS support team

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

cds-question@unistra.frdwarf-galaxiesmultiple-starsspectroscopyvisible-astronomyastrometryradial-velocityeffective-temperaturemetallicityWe present new MMT/Hectochelle spectroscopic measurements for 257 stars observed along the line of sight to the ultrafaint dwarf galaxy Triangulum II (Tri II). Combining results from previous Keck/DEIMOS spectroscopy, we obtain a sample that includes 16 likely members of Tri II, with up to 10 independent redshift measurements per star. To this multi-epoch kinematic data set, we apply methodology that we develop in order to infer binary orbital parameters from sparsely sampled radial velocity curves with as few as two epochs. For a previously identified (spatially unresolved) binary system in Tri II, we infer an orbital solution with period 296.0^+3.8^_-3.3_ d, semimajor axis 1.12^+0.41^_-0.24_ au, and systemic velocity -380.0 +/- 1.7 km/s that we then use in the analysis of Tri II's internal kinematics. Despite this improvement in the modelling of binary star systems, the current data remain insufficient to resolve the velocity dispersion of Tri II. We instead find a 95 per cent confidence upper limit of {sigma}_v_ <~ 3.4 km/s.2022MNRAS.514.1706Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/514/1706CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/350 : Gaia EDR3 (Gaia Collaboration, 2020)II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+,2016)J/A+A/657/A54 : Local Group Gaia eDR3 systemic motions (Battaglia+, 2022)J/AJ/156/257 : Spectroscopy of RGB stars in Draco & Ursa MinorJ/ApJ/870/83 : Abundances in the ultra-faint dwarf gal. GruI & TriIIJ/ApJ/838/83 : Radial velocities, abundances & membership in TriIIJ/MNRAS/490/3508 : The Southern Stellar Stream Sp. Survey (S^5^) (Li+, 2019)J/MNRAS/495/3022 : Stellar populations of the Ursa Minor dSph galaxyJ/MNRAS/448/2717 : Bayesian analysis of resolved stellar spectra (Walker+,2015)https://zenodo.org/records/6561483 : data of this work in zenodohttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/514/1706https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/514/1706http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/514/1706https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/514/1706https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/514/1706http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/514/1706GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/514/1706/tabled1 (Individual observations of Tri II members taken with MMT Hectochelle spectrograph)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/514/1706/tabled1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/514/1706/tabled1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/514/1706/tabled1?GETtext/xml+votable180.050000true33.150536.14861305555560.005555555555555556Cone search capability for table J/MNRAS/514/1706/tabled2 (Individual observations of Tri II members from Keck DEIMOS used in this analysis after a fixed amount of 1.33 +/- 0.33 km/s zero-point offset correction from each velocity measurement)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/514/1706/tabled2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/514/1706/tabled2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/514/1706/tabled2?GETtext/xml+votable180.050000true33.259166736.20908360.0055555555555555566/2341 2343 2352 2354https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/514/1706?format=asciiOpticaldefaultJ/MNRAS/514/1706/tabled1Individual observations of Tri II members taken with MMT Hectochelle spectrographrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaEDR3Unique source identifier from GaiaEDR3 (source_id)meta.id;meta.mainKCS2015? Identifier number [KCS2015] NNN from Kirby et al. 2015ApJ...814L...7K (KCS2015)meta.id.associntnullableMIC2016? Identifier number [MIC2016] NN from Martin et al. 2016ApJ...818...40M (MIC2016)meta.id.associntnullableMemb[0/1] Tri II membership flag 1 for true with 13 objects and 0 for false with 282 objects, refer to section 2.4 (member)meta.code.errorintRA_ICRSRight ascension (ICRS) at Ep=2016.0 (ra_deg)degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2016.0 (dec_deg)degpos.eq.dec;meta.mainHJDHeliocentric Julian Day (hjd)dtime.epoch;pos.heliocentricdoubleSNRSignal to noise ratio from MMT Hectochelle observations see section 2.1 (sn_ratio)meta.ref;pos.framedoublevLOSHeliocentric line-of-sight velocity (vlos)km/sphys.veloc;pos.heliocentricdoublee_vLOSMean error of vLOS (vlos_error)km/sstat.errordoublevSkewStatistical skewness value of the vLOS velocity (vlos_skew)stat.paramdoublevKurtStatistical Kurtosis value for vLOS velocity (vlos_kurtosis)stat.paramdoubleTeffEffective temperature (teff)Kphys.temperature.effectivedoublee_TeffMean uncertainty of Teff (teff_error)Kstat.error;phys.temperature.effectivedoubleTSkewStatistical skewness value of the Teff temeprature (teff_skew)stat.paramdoubleTKurtStatistical Kurtosis value for Teff temeprature (teff_kurtosis)stat.paramdoubleloggSurface gravity (logg)log(cm.s**-2)phys.gravitydoublee_loggMean uncertainty of logg (logg_error)log(cm.s**-2)stat.errordoublegSkewStatistical skewness value of the logg surface gravity (logg_skew)stat.paramdoublegKurtStatistical Kurtosis value for logg surface gravity (logg_kurtosis)stat.paramdouble[Fe/H]Iron to hydrogen abundance ratio (feh)log(Sun)phys.abund.Fe;arith.ratiodoublee_[Fe/H]Mean uncertainty of [Fe/H] (feh_error)log(Sun)stat.error;phys.abund.Fedouble[Fe/H]SkewStatistical skewness value of the [Fe/H] abundance ratio (feh_skew)stat.paramdouble[Fe/H]KurtStatistical Kurtosis value for [Fe/H] abundance ratio (feh_kurtosis)stat.paramdoubleq_[Fe/H][0/1] The [Fe/H] observation data quality, 1 for yes with 207 cases on 295 (feh_qual) (1)meta.code.qual;phys.abund.FeintJ/MNRAS/514/1706/tabled2Individual observations of Tri II members from Keck DEIMOS used in this analysis after a fixed amount of 1.33 +/- 0.33 km/s zero-point offset correction from each velocity measurementSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKCS2015? Identifier number [KCS2015] NNN from Kirby et al. 2015ApJ...814L...7K (KCS2015)meta.id.associntnullableMIC2016? Identifier number [MIC2016] NN from Martin et al. 2016ApJ...818...40M (MIC2016)meta.id;meta.mainintnullableRA_ICRSRight ascension (ICRS) at Ep=2016.0 (RAICRS)degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2016.0 (DecICRS)degpos.eq.dec;meta.mainHJDHeliocentric Julian Day (HJD)dtime.epoch;pos.heliocentricdoublevLOSHeliocentric line-of-sight velocity (vlos)km/sphys.veloc;pos.heliocentricfloate_vLOSMean error of vLOS (vlos_error)km/sstat.errorfloat