J/AJ/124/1486ivo://CDS.VizieR/J/AJ/124/1486doi:10.26093/cds/vizier.51241486CDSMochejska B.J.Kaluzny J.Thompson I.Pych W.2023-04-06T16:50:51Z2006-11-12T08:15:03ZCDS support team

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

cds-question@unistra.frglobular-star-clustersvisible-astronomybroad-band-photometrywhite-dwarf-starsWe present UBV color-magnitude diagrams (CMDs) for the globular cluster M4. The CMDs show a sequence of four luminous blue stars (V<20, U-V<-0.6), which appear to be cluster hot subdwarfs. We present spectra for the three brightest ones. We also note the presence of a population of faint blue objects, likely to be hot, young white dwarfs belonging to the cluster. We have selected five objects above V=22mag, bright enough for follow-up ground-based spectroscopy, and present their coordinates and finding charts. We show a spectrum for variable V46, which suggests that it is a hot subdwarf, along with a new light curve obtained with the ISIS image subtraction package. The light curve is unstable, but only one period of variability is apparent. Two new variables have been discovered, both located on the cluster red giant branch. We also present a differential E(B-V) reddening map and a fiducial sequence for the main sequence, subgiant branch, and red giant branch on the V/B-V CMD for a selected region with uniform reddening. Based on a comparison with the M5 fiducial sequence, we obtain a reddening estimate of E(B-V)=0.41mag toward M4, consistent with previous determinations.2002AJ....124.1486Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/124/1486CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/PAZh/22/847 : Identification and coordinates in M4 (Shokin+, 1996)J/AJ/114/189 : M 4 CCD photometry (Alcaino+, 1997)J/ApJS/120/265 : HST photometry of M4 (Ibata+, 1999)J/AJ/127/2771 : HST proper-motions of M4 main-sequence stars (Richer+, 2004)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/124/1486https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/124/1486http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/124/1486https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/124/1486https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/124/1486http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/124/1486GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/124/1486/m4wd (UBV photometry and astrometry of the white dwarfs)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/124/1486/m4wd?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/124/1486/m4wd?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/124/1486/m4wd?GETtext/xml+votable180.050000true245.89291-26.577360.005555555555555556Cone search capability for table J/AJ/124/1486/m4ubv (Astrometry and UBV photometry for 12121 stars in M4)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/124/1486/m4ubv?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/124/1486/m4ubv?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/124/1486/m4ubv?GETtext/xml+votable180.050000true245.80760194-26.512660.0055555555555555566/42955https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/124/1486?format=asciiOpticaldefaultJ/AJ/124/1486/m4wdUBV photometry and astrometry of the white dwarfse_U-B? rms uncertainty on U-Bmagstat.error;phot.color;em.opt.UfloatnullableU-V? Johnson U-V colour indexmagphot.color;em.opt.U;em.opt.VfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMKTWDSequential WD number, Cl* NGC 6121 MKTWD NN in Simbadmeta.id;meta.mainintVmagJohnson V magnitudemagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on Vmagmagstat.error;phot.mag;em.opt.VfloatB-V? Johnson B-V colour indexmagphot.color;em.opt.B;em.opt.Vfloatnullablee_B-V? rms uncertainty on B-Vmagstat.error;phot.color;em.opt.BfloatnullableU-B? Johnson U-B colour indexmagphot.color;em.opt.U;em.opt.Bfloatnullablee_U-V? rms uncertainty on U-Vmagstat.error;phot.color;em.opt.UfloatnullableClass[A-C] Class of the object (1)meta.code.classcharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainJ/AJ/124/1486/m4ubvAstrometry and UBV photometry for 12121 stars in M4recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMKTSequential number, Cl* NGC 6121 MKT NNNNN in Simbadmeta.recordintXposX positionpixpos.cartesian.x;instr.detfloatYposY positionpixpos.cartesian.y;instr.detfloatVmagJohnson V magnitudemagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on Vmagmagstat.error;phot.mag;em.opt.VfloatB-V? Johnson B-V colour indexmagphot.color;em.opt.B;em.opt.Vfloatnullablee_B-V? rms uncertainty on B-Vmagstat.error;phot.color;em.opt.BfloatnullableU-B? Johnson U-B colour indexmagphot.color;em.opt.U;em.opt.Bfloatnullablee_U-B? rms uncertainty on U-Bmagstat.error;phot.color;em.opt.UfloatnullableU-V? Johnson U-V colour indexmagphot.color;em.opt.U;em.opt.Vfloatnullablee_U-V? rms uncertainty on U-Vmagstat.error;phot.color;em.opt.UfloatnullableNoteHot subdwarf candidate (BN) or Variable (VNN) identificationmeta.notecharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.main