J/AJ/116/1757ivo://CDS.VizieR/J/AJ/116/1757doi:10.26093/cds/vizier.51161757CDSGuhathakurta P.Webster Z.T.Yanny B.Schneider D.P.Bahcall J.N.2023-04-06T16:50:29Z1999-04-07T14:26:05ZCDS support team

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

cds-question@unistra.frglobular-star-clustersvisible-astronomybroad-band-photometryWe present F555W (V), F439W (B), and F336W (U) photometry of 9507 stars in the central 2' of the dense, post-core-collapse cluster M30 (NGC 7099) derived from Hubble Space Telescope Wide Field Planetary Camera 2 images. These data are used to study the mix of stellar populations in the central region of the cluster. Forty-eight blue straggler stars are identified; they are found to be strongly concentrated toward the cluster center. The specific frequency of blue stragglers, F_BSS_=N(BSS)/N(V<V_HB_+2), is 0.25+/-0.05 in the inner region of M30 (r<20"), significantly higher than the frequency found in other clusters: F_BSS_=0.05-0.15. The shape of M30's blue straggler luminosity function resembles the prediction of the collisional formation model, and is inconsistent with the binary merger model of Bailyn & Pinsonneault (1995ApJ...439..705B). An unusually blue star (B=18.6, B-V=-0.97), possibly a cataclysmic variable based on its color, is found about 1.2" from the crowded cluster center; the photometric uncertainty for this star is large, however, because of the presence of a very close neighbor. Bright red giant stars (B<16.6) appear to be depleted by a factor of 2-3 in the inner r<10" relative to fainter giants, subgiants, and main-sequence turnoff stars (95% significance). We confirm that there is a radial gradient in the color of the overall cluster light, going from B-V~0.82 at r~1' to B-V~0.45 in the central 10". The central depletion of the bright red giants is responsible for about half of the observed color gradient; the rest of the gradient is caused by the relative underabundance of faint red main-sequence stars near the cluster center (presumably a result of mass segregation). The luminosity function of M30's evolved stars does not match the luminosity function shape derived from standard stellar evolutionary models: the ratio of the number of bright giants to the number of turnoff stars in the cluster is 30% higher than predicted by the model (3.8{sigma} effect), roughly independent of red giant brightness over the range M_V_=-2 to +2.1998AJ....116.1757Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/116/1757CatalogResearchIsServedByTAP 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)J/AJ/113/669 : Stars in M13 core (Cohen+ 1997)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/116/1757https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/116/1757http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/116/1757https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/116/1757https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/116/1757http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/116/1757GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/116/1757/table1 (M 30 stellar photometry and astrometry)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/116/1757/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/116/1757/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/116/1757/table1?GETtext/xml+votable180.050000true325.0767175-23.16918250.005555555555555556HST6/48434https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/116/1757?format=asciiOpticaldefaultJ/AJ/116/1757/table1M 30 stellar photometry and astrometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGWYIdentification number (1)meta.id;meta.mainintoRARelative right ascension to star 3611 (J2000) (2)arcsecpos.eq.ra;arith.difffloatoDERelative declination to star 3611 (J2000) (2)arcsecpos.eq.dec;arith.difffloatrProjected distance from the cluster centroid (3)arcsecpos.angDistancefloatVmagV magnitudemagphot.mag;em.opt.VfloatB-VB-V colour indexmagphot.color;em.opt.B;em.opt.VfloatU-V? U-V colour indexmagphot.color;em.opt.U;em.opt.Vfloatnullable_RAComputed Right Ascension for Equinox: J2000degpos.eq.ra;meta.main_DEComputed Declination for Equinox: J2000degpos.eq.dec;meta.main