J/A+A/648/A78ivo://CDS.VizieR/J/A+A/648/A78doi:10.26093/cds/vizier.36480078CDSPrudil Z.Hanke M.Lemasle B.Crestani J.Braga V.F.Fabrizio M.,Koch-Hansen A. J.Bono G.Grebel E.K.Matsunaga N.Marengo M.,da Silva R.Dall'Ora M.Martinez-Vazquez C.E.Altavilla G.Lala H.,Chaboyer B.Ferraro I.Fiorentino G.Gilligan C. Nonino M.Thevenin F.2022-07-07T12:06:20Z2021-04-22T12:47:57ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyvariable-starsstellar-distanceradial-velocityWe present a chemo-dynamical study of the Orphan stellar stream using a catalog of RR Lyrae pulsating variable stars for which photometric, astrometric, and spectroscopic data are available. Employing low-resolution spectra from the Sloan Digital Sky Survey (SDSS), we determined line-of-sight velocities for individual exposures and derived the systemic velocities of the RR Lyrae stars. In combination with the stars' spectroscopic metallicities and Gaia EDR3 astrometry, we investigated the northern part of the Orphan stream. In our probabilistic approach, we found 20 single mode RR Lyrae variables likely associated with the Orphan stream based on their positions, proper motions, and distances. The acquired sample permitted us to expand our search to nonvariable stars in the SDSS dataset, utilizing line-of-sight velocities determined by the SDSS. We found 54 additional nonvariable stars linked to the Orphan stream. The metallicity distribution for the identified red giant branch stars and blue horizontal branch stars is, on average, -2.13+/-0.05dex and -1.87+/-0.14dex, with dispersions of 0.23 and 0.43dex, respectively. The metallicity distribution of the RR Lyrae variables peaks at -1.80+/-0.06dex and a dispersion of 0.25dex. Using the collected stellar sample, we investigated a possible link between the ultra-faint dwarf galaxy Grus II and the Orphan stream. Based on their kinematics, we found that both the stream RR Lyrae and Grus II are on a prograde orbit with similar orbital properties, although the large uncertainties on the dynamical properties render an unambiguous claim of connection difficult. At the same time, the chemical analysis strongly weakens the connection between both. We argue that Grus II in combination with the Orphan stream would have to exhibit a strong inverse metallicity gradient, which to date has not been detected in any Local Group system.2021A&A...648A..78Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/648/A78CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/350 : Gaia Early Data Release 3 (Gaia EDR3) (Lindegren+ 2020)V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)J/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008)J/AJ/153/204 : RR Lyrae stars from the PS1 3{pi} survey (Sesar+, 2017)J/ApJ/765/154 : RR Lyrae stars in the Catalina Sky Survey (Drake+, 2013)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/648/A78https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/648/A78http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/648/A78https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/648/A78https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/648/A78http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/648/A78GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/648/A78/tabled1 (RR Lyrae stars in Orphan stream)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/648/A78/tabled1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/648/A78/tabled1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/648/A78/tabled1?GETtext/xml+votable180.050000true146.057822129874740.22071049284680.005555555555555556Cone search capability for table J/A+A/648/A78/tabled2 (Non variable stars in Orphan stream)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/648/A78/tabled2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/648/A78/tabled2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/648/A78/tabled2?GETtext/xml+votable180.050000true151.609043020175121.04929336779610.0055555555555555565/1420 1447 6/4432-4434 4441 4443-4444 4467-4468 4470 4477-4479 5162-5163 5248-5250 5289 5292 5295 5636 5639 5648 5659 5671 5686 5688 5690-5692 5694 5776 5781-5782 5785 5787 5811 7185 7189 7234 27642https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/648/A78?format=asciidefaultJ/A+A/648/A78/tabled1RR Lyrae stars in Orphan streamrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObjIDSDSS source IDmeta.id;meta.mainn_ObjID[*] * for star not used as reference sample in Sect. 4.2meta.notecharGaiaEDR3Gaia EDR3 source IDmeta.idRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.maindDistancepcpos.distancefloate_dUncertainty on distancepcstat.errorfloatVsysSystemic velocitykm/sphys.velocfloate_VsysUncertainty on systemic velocitykm/sstat.errorfloatVCSSMean V band magnitude (Catalina photometry)magphot.mag;em.opt.Vfloate_VCSSUncertainty on mean V band magnitudemagstat.errorfloatSimbadSimbad column added by the CDSmeta.ref.urlcharPPulsation perioddtime.perioddoubleM0Time of brightness maximadtime.epochdoubleAmpVCSSPulsation amplitude (Catalina photometry)magsrc.var.amplitudedoubleTypePulsation RR Lyrae typemeta.notechar[Fe/H]Metallicityphys.abund.ZfloatP(A/B)The conditional prob. of membershipmeta.code.memberfloatNote[K19 -] Known from Koposov et al. (2019MNRAS.485.4726K)meta.notecharJ/A+A/648/A78/tabled2Non variable stars in Orphan streamRVAdopted radial velocitykm/sphys.veloc;pos.heliocentricfloatSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObjIDSDSS source IDmeta.id;meta.mainGaiaEDR3Gaia EDR3 source IDmeta.idRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.maine_RVUncertainty on adopted radial velocitykm/sstat.errorfloatgmagg-band magnitudemagphot.mag;em.opt.Bfloate_gmag? Uncertainty on g-band magnitudemagstat.error;phot.magfloatnullableTeffAdopted Effective temperatureKphys.temperature.effectivefloate_TeffUncertainty on adopted effective temperatureKstat.error;phys.temperature.effectivefloat[Fe/H]Adopted Metallicityphys.abund.Zfloate_[Fe/H]Uncertainty on adopted metallicitystat.error;phys.abund.FefloatloggAdopted Surface gravityphys.gravityfloate_loggUncertainty on adopted surface gravitystat.errorfloatP(A/B)The conditional probability of membershipstat.probabilityfloat