J/A+A/693/A69ivo://CDS.VizieR/J/A+A/693/A69doi:10.26093/cds/vizier.36930069CDSAwad P.Li T.S.Erkal D.Peletier R.F.Bunte K.Koposov S.E.,Li A.Balbinot E.Smith R.Canducci M.Tino P.Senkevich A.M.,Cullinane L.R.Da Costa G.S.Ji A.P.Kuehn K.Lewis G.F.,Pace A.B.Zucker D.B.Bland-Hawthorn J.Limberg G.Martell S.L.,McKenzie M.Yang Y.Usman S.A.2026-03-03T20:01:07Z2025-01-03T15:23:00ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyglobular-star-clustershalo-starsvisible-astronomyAs globular clusters (GCs) orbit the Milky Way, their stars are tidally stripped forming tidal tails that follow the orbit of the cluster around the Galaxy. The morphology of these tails is complex and shows correlations with the phase of orbit and the orbital angular velocity, especially for GCs on eccentric orbits. Here, we focus on two GCs, NGC 1261 and NGC 1904, that have potentially been accreted alongside Gaia-Enceladus and that have shown signatures of having, in addition to tidal tails, structures formed by distributions of extra-tidal stars that are misaligned with the general direction of the clusters' respective orbits. To provide an explanation for the formation of these structures, we make use of spectroscopic measurements from the Southern Stellar Stream Spectroscopic Survey (S5) as well as proper motion measurements from Gaia's third data release (DR3), and apply a Bayesian mixture modelling approach to isolate high-probability member stars. We recover extra-tidal features similar to those found in Shipp et al. (2018ApJ...862..114S) surrounding each cluster. We conduct N-body simulations and compare the expected spatial distribution and variation in the dynamical parameters along the orbit with those of our potential member sample. Furthermore, we use Dark Energy Camera (DECam) photometry to inspect the distribution of the member stars in the color-magnitude diagram (CMD). We find that potential members agree reasonably with the N-body simulations and that the majority of them follow a simple stellar population-like distribution in the CMD which is characteristic of GCs. We link the extra-tidal features with their orbital properties and find that the presence of the tails agrees well with the theory of stellar stream formation through tidal disruption. In the case of NGC 1904, we clearly detect the tidal debris escaping the inner and outer Lagrange points which are expected to be prominent when at or close to the apocenter of its orbit. Our analysis allows for further exploration of other GCs in the Milky Way that exhibit similar extra-tidal features.2025A&A...693A..69Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/693/A69CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/693/A69https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/693/A69http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/693/A69https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/693/A69https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/693/A69http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/693/A69GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/693/A69/ngc1261 (Potential members of NGC 1261 (table B1))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/693/A69/ngc1261?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/693/A69/ngc1261?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/693/A69/ngc1261?GETtext/xml+votable180.050000true47.885-55.6330.005555555555555556Cone search capability for table J/A+A/693/A69/ngc1904 (Potential members of NGC 1904 (table B2))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/693/A69/ngc1904?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/693/A69/ngc1904?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/693/A69/ngc1904?GETtext/xml+votable180.050000true81.104-24.870.0055555555555555565/5254 8408 6/21001 21004-21005 21007 21009-21011 21014-21015 21020-21022 21041 21045 21056-21057 21059 21064 33585-33587 33597 33612 33636 33638 33640-33641 33644-33645 33684https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/693/A69?format=asciiOpticaldefaultJ/A+A/693/A69/ngc1261Potential members of NGC 1261 (table B1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3Gaia star identifiermeta.id;meta.mainRA_ICRSGaia right ascension (ICRS) at Ep=2016.0degpos.eq.ra;meta.mainDE_ICRSGaia declination (ICRS) at Ep=2016.0degpos.eq.dec;meta.mainpmRAGaia proper motion in RAmas/yrpos.pm;pos.eq.rafloatpmDEGaia proper motion in DEmas/yrpos.pm;pos.eq.decfloatBp-RpGaia color (G_BP_-G_RP_)magphot.color;em.opt.B;em.opt.RfloatSimbadSimbad column added by the CDSmeta.ref.urlchar_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.raindexed_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.decindexedGmagGaia magnitudemagphot.mag;em.optfloatgmagDECam g band magnitudemagphot.mag;em.opt.Bfloatg-rDECam g-r colormagphot.color;em.opt.B;em.opt.RfloatRVS5 radial velocitykm/sphys.veloc;pos.heliocentricfloate_RVS5 error on radial velocitykm/sstat.errorfloat[Fe/H]S5 [Fe/H] metallicityphys.abund.Zfloate_[Fe/H]S5 [Fe/H] error on the metallicitystat.error;phys.abund.FefloatPmembMembership probabilitystat.probabilityfloatJ/A+A/693/A69/ngc1904Potential members of NGC 1904 (table B2)SimbadSimbad column added by the CDSmeta.ref.urlchar_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.raindexed_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.decindexedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3Gaia star identifiermeta.id;meta.mainRA_ICRSGaia right ascension (ICRS) at Ep=2016.0degpos.eq.ra;meta.mainDE_ICRSGaia declination (ICRS) at Ep=2016.0degpos.eq.dec;meta.mainpmRAGaia proper motion in RAmas/yrpos.pm;pos.eq.rafloatpmDEGaia proper motion in DEmas/yrpos.pm;pos.eq.decfloatBp-RpGaia color (G_BP_-G_RP_)magphot.color;em.opt.B;em.opt.RfloatGmagGaia magnitudemagphot.mag;em.optfloatgmagDECam g band magnitudemagphot.mag;em.opt.Bfloatg-rDECam g-r colormagphot.color;em.opt.B;em.opt.RfloatRVS5 radial velocitykm/sphys.veloc;pos.heliocentricfloate_RVS5 error on radial velocitykm/sstat.errorfloat[Fe/H]S5 [Fe/H] metallicityphys.abund.Zfloate_[Fe/H]S5 [Fe/H] error on the metallicitystat.error;phys.abund.FefloatPmembMembership probabilitystat.probabilityfloat