J/ApJ/748/91ivo://CDS.VizieR/J/ApJ/748/91doi:10.26093/cds/vizier.17480091CDSContreras Ramos R.Ferraro F.R.Dalessandro E.Lanzoni B.Rood R.T.2013-12-05T10:09:18Z2013-11-15T14:37:51ZCDS support team

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

cds-question@unistra.frglobular-star-clustershst-photometryWe have used a combination of multiband high-resolution and wide-field ground-based observations to image the Galactic globular cluster M75 (NGC 6864). The extensive photometric sample covers the entire cluster extension, from the very central regions out to the tidal radius, allowing us to determine the center of gravity and to construct the most extended star density profile ever published for this cluster. We also present the first detailed star counts in the very inner regions. The star density profile is well reproduced by a standard King model with core radius r_c_~5.4" and intermediate-high concentration c~1.75. The present paper presents a detailed study of the blue straggler star (BSS) population and its radial distribution. A total of 62 bright BSSs (with m_F255W_<~21, corresponding to m_F555W_<~20) have been identified, and they have been found to be highly segregated in the cluster core. No significant upturn in the BSS frequency has been observed in the outskirts of M75, in contrast to several other clusters studied with the same technique. This observational fact is quite similar to what has been found in M79 (NGC 1904) by Lanzoni et al. (2007ApJ...663.1040L). Indeed, the BSS radial distributions in the two clusters are qualitatively very similar, even if in M75 the relative BSS frequency seems to decrease significantly faster than in M79: it decreases by a factor of five (from 3.4 to 0.7) within 1r_c_. Such evidence indicates that the vast majority of the cluster heavy stars (binaries) have already sunk to the core.2012ApJ...748...91Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/748/91CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/hst : HST Archived Exposures Catalog (STScI, 2007)J/A+A/554/A81 : Abundances of 16 giants in M75 (Kacharov+, 2013)J/A+A/483/183 : Catalogue of Blue Stragglers (Moretti+, 2008)J/ApJ/681/311 : Blue stragglers in NGC 2419 (Dalessandro+, 2008)J/A+A/469/529 : UBVI photometry of NGC 6864 (Kravtsov+, 2007)J/ApJ/663/267 : Blue straggler population of M5 (Lanzoni+, 2007)J/ApJ/522/983 : M80 blue straggler stars (Ferraro+, 1999)J/A+A/324/915 : Blue stragglers in M3 (Ferraro+ 1997)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/748/91https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/748/91http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/748/91https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/748/91https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/748/91http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/748/91GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/748/91/table1 (The blue straggler star (BSS) population of M75)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/748/91/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/748/91/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/748/91/table1?GETtext/xml+votable180.050000true301.52025-21.921735830.0055555555555555566/486982.0401237512456292e-19 8.340942757590715e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/748/91?format=asciiOpticaldefaultJ/ApJ/748/91/table1The blue straggler star (BSS) population of M75SeqRunning sequence numbermeta.id;meta.mainintF336W[19.19/20.61]? HST/WFPC2 F336W filter magnitudemagphot.mag;em.opt.UfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000[301.49/301.56] Right Ascension (J2000) (1)degpos.eq.ra;meta.mainDEJ2000[-21.95/-21.90] Declination (J2000) (1)degpos.eq.dec;meta.mainDist[0.401/143.024] Distance from cluster centerarcsecpos.angDistancefloatF225W[19.50/21.34]? HST/WFPC2 F255W filter magnitudemagphot.mag;em.UV.200-300nmfloatnullableF555W[18.65/20.21] HST/WFPC2 F555W filter magnitudemagphot.mag;em.opt.VfloatF814W[18.34/19.23]? HST/WFPC2 F814W filter magnitudemagphot.mag;em.opt.Ifloatnullable