J/A+A/689/A232ivo://CDS.VizieR/J/A+A/689/A232doi:10.26093/cds/vizier.36890232CDSCruz Reyes M.Anderson R.I.2024-11-29T20:05:46Z2024-09-13T12:52:34ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyglobular-star-clustersgalaxy-classification-systemsvisible-astronomyWe homogeneously measured the elliptical shapes of 163 Globular Clusters (GCs) using the on-sky distribution of their cluster members and the third data release of the ESA mission Gaia (DR3). The astrometry enables the differentiation of stars within clusters from those in the field. This feature is particularly valuable for clusters located in densely populated areas of the sky, where the conventional methods for measuring the geometry of the GCs are not applicable. The median axial ratio of our full sample is <b/a>=0.935^+0.033^_-0.090_, and 0.986^+0.009^_-0.004_ for the subset of 11 GCs previously studied based on HST imaging. We investigated whether the minor axis of the ellipses can be interpreted as a pseudo-rotation axis by comparing it to measurements of cluster rotation. Using the radial velocities from Gaia, we detected rotation for three clusters, NGC 5139, NGC 104, and NGC 6341, and observed alignment between the pseudo-rotation axis and the 2D projection of the real rotation axis. To expand the set of clusters for which rotation has been detected, we analyzed multiple literature references. Depending on the reference used for comparison, we observed alignment in between 76% to 100% of the clusters. The lack of alignment observed in some clusters may be linked to the fact that some studies analyze different scales, since multiple studies have demonstrated that the orientation of rotation varies with the distance from the center. We estimate that the next Gaia release will increase the number of stars with radial velocities in GCs from ~10000 in Gaia DR3 to ~55000 in Gaia DR4. This will enable the measurement of rotation and ellipticities at identical angular scales for additional clusters, which will help to clarify whether the previously mentioned alignment occurs across all clusters.2024A&A...689A.232Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/689/A232CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/671/A106 : Galactic globular cluster stars RVs (Martens+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/689/A232https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/689/A232http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/689/A232https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/689/A232https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/689/A232http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/689/A232GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/689/A232/tablea1 (Ellipticity of globular clusters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/689/A232/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/689/A232/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/689/A232/tablea1?GETtext/xml+votable180.050000true58.7604167-49.61444440.0055555555555555560/https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/689/A232?format=asciiOpticaldefaultJ/A+A/689/A232/tablea1Ellipticity of globular clustersSimbadNameSimbad column added by the CDSmeta.idcharnullableNPCANumber of stars used to determine the PCA parametersmeta.numberintNM23? Number of stars used by Martens et al., 2023A&A...671A.106M, Cat. J/A+A/671/A106meta.numberintnullablethetaM23? Angular scale used by Martens et al., 2023A&A...671A.106M, Cat. J/A+A/671/A106 to measure rotationdegphys.angSizefloatnullableNF14? Number of stars used by Fabricius et al. 2014ApJ...787L..26Fmeta.numberintnullablethetaF14? Angular scale used by Fabricius et al. 2014ApJ...787L..26F to determine the ellipticitiesdegphys.angSizefloatnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainClusterCluster namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordinteEllipticity determined in this studysrc.ellipticityfloate_eUncertainty in the ellipticitystat.errorfloateC10? Ellipticity determined by Chen & Chen, 2010ApJ...721.1790Csrc.ellipticityfloatnullablee_eC10? Uncertainty in the Chen & Chen, 2010ApJ...721.1790C ellipticitystat.errorfloatnullableeH10? Ellipticity determined by Belokurov et al., 2024MNRAS.528.3198Bsrc.ellipticityfloatnullableeF14? Ellipticity determined by Fabricius et al. 2014ApJ...787L..26Fsrc.ellipticityfloatnullablee_eF14? Uncertainty in the Fabricius et al. 2014ApJ...787L..26F ellipticitystat.errorfloatnullablethetaAngular scale used to determine the PCA parametersdegphys.angSizefloatJ/A+A/689/A232/tablea3Position anglesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPAPosition angle of the PCA ellipsedegpos.posAngfloate_PAUncertainty in the position angledegstat.errorfloatPAkF14? Kinematic position angle of Fabricius et al. 2014ApJ...787L..26Fdegpos.posAngfloatnullablee_PAkF14? Uncertainty in the kinematic position angle of Fabricius et al. 2014ApJ...787L..26Fdegstat.errorfloatnullablePAphF14? Photometric position angle of Fabricius et al. 2014ApJ...787L..26Fdegpos.posAngfloatnullablee_PAphF14? Uncertainty in the photometric position angle of Fabricius et al. 2014ApJ...787L..26Fdegstat.errorfloatnullablePAS19? Position angle of Sollima et al., 2019MNRAS.485.1460Sdegpos.posAngfloatnullablee_PAS19? Uncertainty in the position angle of Sollima et al., 2019MNRAS.485.1460Sdegstat.errorfloatnullablePAM23? Position angle of Martens et al., 2023A&A...671A.106M, Cat. J/A+A/671/A106degpos.posAngfloatnullableE_PAM23? Upper value of the uncertainty in the position angle of Martens et al., 2023A&A...671A.106M, Cat. J/A+A/671/A106degstat.error;stat.maxfloatnullablee_PAM23? Lower value of the uncertainty in the position angle of Martens et al., 2023A&A...671A.106M, Cat. J/A+A/671/A106degstat.errorfloatnullableClusterCluster namemeta.id;meta.mainchar