J/AJ/113/669ivo://CDS.VizieR/J/AJ/113/669doi:10.26093/cds/vizier.51130669CDSCohen R.L.Guhathakurta P.Yanny B.Schneider D.P.Bahcall J.N.2023-04-06T16:50:25Z2002-07-11T21:58:34ZCDS support team

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

cds-question@unistra.frglobular-star-clustersphotometryWe study the dense core of the globular cluster Messier 13 (NGC 6205) using pre-refurbishment Planetary Camera-I images obtained with the Hubble Space Telescope. Short exposures (60s) through the F555W and F785LP filters (similar to Johnson V and I, respectively) have been used to obtain V and I photometry of 2877 stars brighter than V~20 in a 1.25arcmin^2^ region of the cluster including its core and extending out to r~66arcsec (2.3pc) from its center. The sample is complete to V~=18.3 (the main sequence turnoff) and the 1{sigma} photometric error is about 0.1mag. We find 15 blue straggler star candidates and 10 other possible blue stragglers in this region of M13. Their specific frequency is in the range F_(BSS)=0.04-0.07, comparable to what is observed near the centers of other dense clusters. A comparison between M13's observed V band stellar luminosity function and a theoretical model (Bergbusch & Vandenberg, 1992ApJS...81..163B) for the luminosity function of an old, metal-poor cluster shows that the model predicts too few of the brightest red giants (V~12.5-15) by a factor of two relative to subgiants/turnoff stars (>6{sigma} effect). The radial distributions of red giants, blue stragglers, and subgiants are consistent with one another, and are well fit by a King profile of core radius r_(core)_=38+/-6arcsec (90% confidence limits) or 1.3pc. Stars in the blue horizontal branch of M13, however, appear to be centrally depleted relative to other stellar types. We combine data from three dense ``King model clusters,'' M13, M3, and 47 Tuc, and two post core collapse clusters, M30 and M15, and compare the distributions of various stellar types as a function of (r/r_(half light)_) and (r/r_(core)_). The horizontal branch stars in the combined sample appear to be centrally depleted relative to the giants (97% significance), this depletion is only a 1-2{sigma} effect in each of the clusters taken individually. The blue stragglers in the combined sample are centrally concentrated relative to the giants. (Copyright) 1997 American Astronomical Society.1997AJ....113..669Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/113/669CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/107/1745 : HST UVI photometry of M15. II. (Yanny+, 1994)J/AJ/108/1786 : Blue stragglers + variable stars in M3 (Guhathakurta+, 1994)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/113/669https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/113/669http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/113/669https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/113/669https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/113/669http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/113/669GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/113/669/table1 (Stars in the core of M13)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/113/669/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/113/669/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/113/669/table1?GETtext/xml+votable180.050000true250.399216436.45859750.005555555555555556HST6/9436https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/113/669?format=asciiOpticaldefaultJ/AJ/113/669/table1Stars in the core of M13recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentification numbermeta.id;meta.mainintdRAR.A. J2000 offset from star #5540arcsecpos.eq.ra;arith.difffloatdDEDec. J2000 offset from star #5540arcsecpos.eq.dec;arith.difffloatCCDPC number of the CCDobs.fieldintrAngular distance from center of M13arcsecpos.angDistancefloatF555WF555W magnitudemagphot.mag;em.opt.VfloatF785LP? F785LP magnitudemagphot.mag;em.opt.IfloatnullableVmag? V magnitudemagphot.mag;em.opt.VfloatnullableImag? I magnitudemagphot.mag;em.opt.IfloatnullableV-I? V-I colormagphot.color;em.opt.V;em.opt.Ifloatnullable_RASimbad column added by the CDSdegpos.eq.ra;meta.main_DESimbad column added by the CDSdegpos.eq.dec;meta.main