J/ApJ/911/149ivo://CDS.VizieR/J/ApJ/911/149doi:10.26093/cds/vizier.19110149CDSLi T.S.Koposov S.E.Erkal D.Ji A.P.Shipp N.Pace A.B.Hilmi T.,Kuehn K.Lewis G.F.Mackey D.Simpson J.D.Wan Z.Zucker D.B.,Bland-Hawthorn J.Cullinane L.R.Da Costa G.S.Drlica-Wagner A.,Hattori K.Martell S.L.Sharma S.The S5 Collaboration2023-06-06T08:59:10Z2022-10-25T11:25:15ZCDS support team

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

cds-question@unistra.frstellar-associationsmetallicityradial-velocityhorizontal-branch-starsvariable-starsvisible-astronomyspectroscopyphotometryWe present the first spectroscopic measurements of the ATLAS and Aliqa Uma streams from the Southern Stellar Stream Spectroscopic Survey (S5), in combination with the photometric data from the Dark Energy Survey and astrometric data from Gaia. From the coherence of spectroscopic members in radial velocity and proper motion, we find that these two systems are extremely likely to be one stream with discontinuity in morphology and density on the sky (the "kink" feature). We refer to this entire stream as the ATLAS-Aliqa Uma stream, or the AAU stream. We perform a comprehensive exploration of the effect of baryonic substructures and find that only an encounter with the Sagittarius dwarf ~0.5Gyr ago can create a feature similar to the observed "kink." In addition, we also identify two gaps in the ATLAS component associated with the broadening in the stream width (the "broadening" feature). These gaps have likely been created by small mass perturbers, such as dark matter halos, as the AAU stream is the most distant cold stream known with severe variations in both the stream surface density and the stream track on the sky. With the stream track, stream distance, and kinematic information, we determine the orbit of the AAU stream and find that it has been affected by the Large Magellanic Cloud, resulting in a misalignment between the proper motion and stream track. Together with the Orphan-Chenab Stream, AAU is the second stream pair that has been found to be a single stream separated into two segments by external perturbation.2021ApJ...911..149Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/911/149CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/350 : VLT Survey Telescope ATLAS (Shanks+, 2015)II/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006)J/A+A/466/181 : BVI photometry of Whiting 1 (Carraro+, 2007)J/ApJ/736/146 : Radial velocities of stars in Bootes I (Koposov+, 2011)J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)J/ApJ/757/83 : The Blanco Cosmology Survey (BCS) (Desai+, 2012)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/MNRAS/434/1681 : Extremely metal-poor stars CaII triplet (Carrera+, 2013)J/A+A/561/A87 : FLAMES observations of Terzan 8 (Carretta+, 2014)J/ApJ/834/57 : MW molecular clouds from ^12^CO (Miville-Deschenes+, 2017)J/A+A/616/A10 : Open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)J/ApJ/866/22 : Spectroscopic analysis of Tuc III stream (Li+, 2018)J/MNRAS/481/1195 : Gaia DR2 RRL stars as standard candles (Muraveva+, 2018)J/MNRAS/482/5138 : Galactic GC mean PMs & velocities (Baumgardt+, 2019)J/AJ/158/223 : RRL members of Pal 5 stellar stream (Price-Whelan+, 2019)J/ApJ/885/3 : Membership in 12 stellar streams from DES (Shipp+, 2019)J/MNRAS/484/2832 : Proper motions of MW globular clusters (Vasiliev, 2019)J/MNRAS/490/3508 : The Southern Stellar Stream Sp. Survey (S^5^) (Li+, 2019)J/AJ/159/287 : Stellar parameters in Oph Stream with MMT (Caldwell+, 2020)J/AJ/160/181 : Chemical abundances in red giants with Magellan (Ji+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/911/149https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/911/149http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/911/149https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/911/149https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/911/149http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/911/149GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/911/149/table1 (A total of 96 spectroscopic members in ATLAS stream and Aliqa Uma stream)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/911/149/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/911/149/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/911/149/table1?GETtext/xml+votable180.050000true9.10964194-20.418631110.005555555555555556Cone search capability for table J/ApJ/911/149/table2 (Blue horizontal branch (BHB) and RR Lyrae (RRL) members in ATLAS stream and Aliqa Uma stream)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/911/149/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/911/149/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/911/149/table2?GETtext/xml+votable180.050000true19.67881694-26.591158060.005555555555555556Cone search capability for table J/ApJ/911/149/table3 (A total of 25 spectroscopic members in Palca stream, found in the ATLAS-Aliqa Uma (AAU) stream fields)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/911/149/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/911/149/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/911/149/table3?GETtext/xml+votable180.050000true33.90582889-34.599403060.0055555555555555565/8830 8913 6/16661 16669-16670 16692 16694 16699-16700 16785 35196-35198 35281 35283-35286 35289 35291-35292 35294 35311-35313 35315-35316 35318 35326 35660 35662 35665 35683-35684 35686 35688-35689 35691 35767 35773 35775 35779 35785-35787 35808 35810-35811 35816 358181.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/911/149?format=asciiOpticaldefaultJ/ApJ/911/149/table1A total of 96 spectroscopic members in ATLAS stream and Aliqa Uma streamrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaGaia DR2 source identifiermeta.id;meta.mainRA_ICRS[9.1/40.4] Gaia DR2 Right Ascension in decimal degrees (ICRS) at Ep=2015.5degpos.eq.ra;meta.mainDE_ICRS[-37.6/-20.4] Gaia DR2 Declination in decimal degrees (ICRS) at Ep=2015.5degpos.eq.dec;meta.mainSNR[2.6/77.5] Signal-to-Noisestat.snrfloatGmag[14.96/19.58] Gaia DR2 G band magnitudemagphot.mag;em.optfloatRVel[-157/-5] Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_RVel[0.6/21] Uncertainty in RVelkm/sstat.error;spect.dopplerVelocfloatSimbadSimbad column added by the CDSmeta.ref.urlchar_RA.icrsRight ascension (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.raindexed_DE.icrsDeclination (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decindexed[Fe/H][-2.71/-1.93]? Metallicitylog(Sun)phys.abund.Zfloatnullablee_[Fe/H][0.1/0.53]? Uncertainty in [Fe/H]log(Sun)stat.error;phys.abund.FefloatnullableDESDisplay data from DES DR2 (II/371) within 0.5"meta.ref.urlcharS5DR1Display data from the S5 DR1 (Li+, 2019, J/MNRAS/490/3508)meta.ref.urlcharJ/ApJ/911/149/table2Blue horizontal branch (BHB) and RR Lyrae (RRL) members in ATLAS stream and Aliqa Uma streamGaiaGaia DR2 source identifiermeta.id;meta.mainSimbadSimbad column added by the CDSmeta.ref.urlchar_RA.icrsRight ascension (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.raindexed_DE.icrsDeclination (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decindexedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRA_ICRS[9.97/38.25] Gaia DR2 Right Ascension in decimal degrees (ICRS) at Ep=2015.5degpos.eq.ra;meta.mainDE_ICRS[-35.82/-20.8] Gaia DR2 Declination in decimal degrees (ICRS) at Ep=2015.5degpos.eq.dec;meta.mainm-M[16.21/17.29] Distance modulusmagphot.mag.distModfloatClTracer identifier (1)src.classcharDESDisplay data from DES DR2 (II/371) within 0.5"meta.ref.urlcharS5DR1Display data from the S5 DR1 (Li+, 2019, J/MNRAS/490/3508)meta.ref.urlcharJ/ApJ/911/149/table3A total of 25 spectroscopic members in Palca stream, found in the ATLAS-Aliqa Uma (AAU) stream fieldsGaiaGaia DR2 source identifiermeta.id;meta.main_RA.icrsRight ascension (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.raindexed_DE.icrsDeclination (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decindexedSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRA_ICRS[29.75/39.6] Gaia DR2 Right Ascension in decimal degrees (ICRS) at Ep=2015.5degpos.eq.ra;meta.mainDE_ICRS[-37.86/-31.5] Gaia DR2 Declination in decimal degrees (ICRS) at Ep=2015.5degpos.eq.dec;meta.mainSNR[2.9/75.3] Signal-to-Noisestat.snrfloatGmag[15.44/19.5] Gaia DR2 G band magnitudemagphot.mag;em.optfloatRVel[81/118] Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_RVel[0.6/34] Uncertainty in RVelkm/sstat.error;spect.dopplerVelocfloat[Fe/H][-2.21/-1.57]? Metallicitylog(Sun)phys.abund.Zfloatnullablee_[Fe/H][0.1/0.34]? Uncertainty in [Fe/H]log(Sun)stat.error;phys.abund.FefloatnullableDESDisplay data from DES DR2 (II/371) within 0.5"meta.ref.urlcharS5DR1Display data from the S5 DR1 (Li+, 2019, J/MNRAS/490/3508)meta.ref.urlchar