J/A+A/469/529ivo://CDS.VizieR/J/A+A/469/529doi:10.26093/cds/vizier.34690529CDSKravtsovV.AlcainoG.MarconiG.Alvarado F.2007-08-19T12:27:35Z2007-08-19T12:24:35ZCDS support team

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

cds-question@unistra.frglobular-star-clustersccd-photometryinfrared-photometryvisible-astronomyWide-band photometryWe carry out and analyze new multi-color photometry of the Galactic globular cluster (GC) M75 in UBVI and focus on the brighter sequences of the color-magnitude diagram (CMD), with particular emphasis on their location in U-based CMD. Specifically, we study the level both of the horizontal (HB) and red giant branches (RGB) relative to the main-sequence turnoff (TO) in the U magnitude. Along with the presented photometry of M75, we use our collection of photometric data on GCs belonging to the metal-poor range, [Fe/H]zw<-1.1dex, obtained from observations with different equipment, but calibrated by standard stars situated in the observed cluster fields. We confirm our earlier finding, and extend it to a larger magnitude range. We demonstrate that Delta(U_TO_^BHB^) expressing the difference in U magnitude between the TO point and the level of the blue HB, near its red boundary, of the metal-poor GCs observed with the EMMI camera of the NTT/ESO telescope is about 0.4-0.5mag smaller as compared to GCs observed with the 100" telescope and 1.3m Warsaw telescope of the Las Campanas Observatory. At the same time, Delta(U_TO_^RGB^), the difference in U magnitude between the TO and RGB inflection (brightest) points, does not show such an apparent dependence on the characteristics of U filters used, but it depends on cluster metallicity. We have shown, for the first time, the dependence of the parameter Delta(U_TO_^RGB^) on [Fe/H] and have estimated its analytical expression, by assuming a linear relation between the parameter and metallicity. Its slope, Delta(U_TO_^RGB^)/Delta[Fe/H]~1.2mag/dex, is approximately a factor of two steeper than that of the dependence of the RGB bump position in the V magnitude on metallicity. The asymptotic giant branch (AGB) clump and features of the RGB luminosity function (LF) of M75 are also discussed. The observations were made on 3 nights, 9-12 October 1998, with the 1.3m Warsaw telescope.2007A&A...469..529Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/469/529CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/469/529https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/469/529http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/469/529https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/469/529https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/469/529http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/469/529GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/469/529/m75phot (Photometric data for 2681 stars in M75)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/469/529/m75phot?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/469/529/m75phot?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/469/529/m75phot?GETtext/xml+votable180.050000true301.48258389-22.026248890.0055555555555555566/48698https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/469/529?format=asciiOpticalInfrareddefaultJ/A+A/469/529/m75photPhotometric data for 2681 stars in M75SeqSequential numbermeta.recordintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintXposx coordinate (1)pixpos.cartesian.x;instr.detfloatYposy coordinate (1)pixpos.cartesian.y;instr.detfloatVmagV magnitudemagphot.mag;em.opt.VfloatUmag? U magnitude (2)magphot.mag;em.opt.UfloatnullableBmag? B magnitude (2)magphot.mag;em.opt.BfloatnullableImagI magnitudemagphot.mag;em.opt.Ifloat_RAPosition computed from a comparison with 2MASS catalog II/246 ({sigma}=0.2'') (right ascension part)degpos.eq.ra;meta.main_DEPosition computed from a comparison with 2MASS catalog II/246 ({sigma}=0.2'') (declination part)degpos.eq.dec;meta.main