J/MNRAS/520/63ivo://CDS.VizieR/J/MNRAS/520/63doi:10.26093/cds/vizier/bg-g8-1zCDSWhitmore B.C.Chandar R.Lee J.C.Floyd M.Deger S.Lilly J.,Minsley R.Thilker D.A.Boquien M.Dale D.A.Henny K.Scheuermann F.,Barnes A.T.Bigiel F.Emsellem E.Glover S.Grasha K.Groves B.,Hannon S.Klessen R.S.Kreckel K.Kruijssen J.M.D.Larson K.L.,Leroy A.Mok A.Pan H.-A.Pinna F.Sanchez-Blazquez P.Schinnerer E.,Sormani M.C.Watkins E.Williams T.2026-08-03T07:32:52Z2026-04-23T09:17:19ZCDS support team

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

cds-question@unistra.frgalaxiesglobular-star-clustersphotometrystellar-agesspectroscopymolecular-physicsvisible-astronomyastrometrymillimeter-astronomysubmillimeter-astronomynarrow-band-photometrystellar-massesextinctionA long-standing problem when deriving the physical properties of stellar populations is the degeneracy between age, reddening, and metallicity. When a single metallicity is used for all the star clusters in a galaxy, this degeneracy can result in 'catastrophic' errors for old globular clusters. Typically, approximately 10-20 per cent of all clusters detected in spiral galaxies can have ages that are incorrect by a factor of 10 or more. In this paper, we present a pilot study for four galaxies (NGC 628, NGC 1433, NGC 1365, and NGC 3351) from the PHANGS-HST survey. We describe methods to correct the age-dating for old globular clusters, by first identifying candidates using their colours, and then reassigning ages and reddening based on a lower metallicity solution. We find that young 'Interlopers' can be identified from their H{alpha} flux. CO (2-1) intensity or the presence of dust can also be used, but our tests show that they do not work as well. Improvements in the success fraction are possible at the ~=15 per cent level (reducing the fraction of catastrophic age-estimates from between 13 and 21 per cent, to between 3 and 8 per cent). A large fraction of the incorrectly age-dated globular clusters are systematically given ages around 100 Myr, polluting the younger populations as well. Incorrectly age-dated globular clusters significantly impact the observed cluster age distribution in NGC 628, which affects the physical interpretation of cluster disruption in this galaxy. For NGC 1365, we also demonstrate how to fix a second major age-dating problem, where very dusty young clusters with E(B - V) > 1.5 mag are assigned old, globular-cluster like ages. Finally, we note the discovery of a dense population of ~=300 Myr clusters around the central region of NGC 1365 and discuss how this results naturally from the dynamics in a barred galaxy.2023MNRAS.520...63Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/520/63CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/512/1294 : HST study of star cluster in LEGUS galaxies (Hannon+, 2022)J/MNRAS/510/32 : Star clusters study in PHANGS-HST galaxies (Deger+, 2022)J/MNRAS/509/180 : GC in 5 nearby spiral galaxies (Lomeli-Nunez+, 2022)J/MNRAS/498/4906 : Pressure components in the central HII regionsJ/MNRAS/404/1639 : MILES base models & new line index system (Vazdekis+, 2010)J/ApJ/909/121 : Young star clusters in NGC1313 with HST obs. (Messa+, 2021)J/ApJ/889/154 : LEGUS & Ha-LEGUS obs. of NGC4449 star clustersJ/ApJ/887/80 : Gas phase oxygen abundances for HII regions (Kreckel+, 2019)J/ApJ/667/L145 : HST Photometry of M82 region B (Smith+, 2007)J/A+A/658/A188 : PHANGS-MUSE sample HII regions catalog (Santoro+, 2022)J/A+A/622/A103 : Python Code Investigating GALaxy Emission (Boquien+, 2019)J/A+A/527/A109 : Dust and PAH emission SEDs of disk galaxies (Popescu+, 2011)J/A+A/416/537 : UBVI and HST photometry of young stellar clustersJ/ApJS/257/43 : PHANGS-ALMA: arcsecond CO(2-1) imaging of galaxiesJ/ApJS/184/1 : Molecular clouds in the LMC by NANTEN. II. (Kawamura+, 2009)J/AJ/163/16 : Multiwavelength study in M33 star clusters (Moeller+, 2022)J/AJ/140/75 : Antennae galaxies (NGC 4038/4039) revisited (Whitmore+,2010)J/AJ/124/1418 : Radio-optical identification of star clustersII/342 : Hubble Source Catalog (V1 and V2) (Whitmore+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/520/63https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/520/63http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/520/63https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/520/63https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/520/63http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/520/63GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/520/63/ngc628 (New hybrid SED age solutions ages, masses and reddenings for cluster class 1 and 2 in NGC 628)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/520/63/ngc628?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/520/63/ngc628?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/520/63/ngc628?GETtext/xml+votable180.050000true24.155934856265315.74145106589620.005555555555555556Cone search capability for table J/MNRAS/520/63/ngc1433 (New hybrid SED age solutions ages, masses and reddenings for cluster class 1 and 2 in NGC 1433)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/520/63/ngc1433?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/520/63/ngc1433?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/520/63/ngc1433?GETtext/xml+votable180.050000true55.5059299832878-47.24490014090330.005555555555555556Cone search capability for table J/MNRAS/520/63/ngc3351 (New hybrid SED age solutions ages, masses and reddenings for cluster class 1 and 2 in NGC 3351)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/520/63/ngc3351?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/520/63/ngc3351?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/520/63/ngc3351?GETtext/xml+votable180.050000true160.962903410862211.66517185817440.005555555555555556Cone search capability for table J/MNRAS/520/63/ngc1365 (New hybrid SED age solutions ages, masses and reddenings for cluster class 1 and 2 in NGC 1365)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/520/63/ngc1365?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/520/63/ngc1365?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/520/63/ngc1365?GETtext/xml+votable180.050000true53.4179421612991-36.16967457368880.0055555555555555566/18398 27514 34343 345313.2082799382822207e-19 4.2441532724171825e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/520/63?format=asciiOpticalMillimeterdefaultJ/MNRAS/520/63/ngc628New hybrid SED age solutions ages, masses and reddenings for cluster class 1 and 2 in NGC 628recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDID number from compact cluster catalog (ID_PHANGS_CLUSTERS_V0_9_1)meta.id;meta.mainintXposX coordinate (PHANGS_X)pixpos.cartesian.x;instr.detdoubleYposY coordinate (PHANGS_Y)pixpos.cartesian.y;instr.detdoubleRAJ2000Right ascension from PHANGS-HST (J2000) (PHANGS_RA)degpos.eq.ra;meta.mainDEJ2000Declination from PHANGS-HST (J2000) (PHANGS_DEC)degpos.eq.dec;meta.mainCIConcentration Index CI as difference magnitude between a vega magnitude in 1 pixel radius minus a vega magnitude in 3 pixel radius (PHANGS_CI)magphot.mag;arith.diff;em.optfloatlogAgeTThe original version 1 of logarithm age estimate with as described in Turner et al. 2021MNRAS.502.1366T (log_PHANGS_AGE_MINCHISQ)log(yr)meta.version;time.agedoublelogM*oOriginal logarithm of mass estimated with Chi2 minimization (log_PHANGS_MASS_MINCHISQ)log(solMass)phys.massfloatE(B-V)The original E(B-V) estimated with Chi2 minimization (PHANGS_EBV_MINCHISQ)magphot.color.excessfloatChiThe reduced phangs chi-sqr value (PHANGS_REDUCED_MINCHISQ)stat.fit.chi2doubleClassThe human cluster classification symmetric as 1 and asymmetric as 2 (PHANGS_CLUSTER_CLASS)meta.code.classfloatU-B? F336W - F438W vega system color magnitude where objects out of field of view, or with negative flux = EMPTY flux (u-b)magphot.color;em.opt.U;em.opt.BdoublenullableB-VF438W - F555W vega system color magnitude (b-v)magphot.color;em.opt.B;em.opt.VdoubleV-IF555W - F814W vega system color magnitude (v-i)magphot.color;em.opt.V;em.opt.IdoubleF555WmagThe F555W total magnitude in vega system (PHANGS_F555W_VEGA_TOT)magphot.mag;em.opt.VdoubleFHaThe Halpha flux estimate where objects out of the Field of View are set to 0 value (HA6562_FLUX)1e-18mW.m**-2.pixel**-1phot.flux;em.line.HalphadoubleICOThe molecular CO (2-1) flux intensity where objects out of the Field of View are set to 1.0E20 value (CO_intensity)K.km/sphot.flux.density;em.line.CO;em.mm.200-400GHzdoublelogAgeHOThe logarithm of the age estimate for Old Globular Cluster=OGC box solution (hybrid_log_age_ogc)log(yr)time.agedoublelogM*HOThe logarithm of the mass estimate for Old Globular Cluster = OGC box solution (hybrid_log_mass_ogc)log(solMass)phys.massfloatE(B-V)HOThe E(B-V) estimate Old Globular Cluster = OGC box solution (hybrid_ebv_ogc)magphot.color.excessfloatlogAgeHVIThe logarithm of the age estimate for VI limit solution (hybrid_log_age_vi)log(yr)time.agedoublelogMHVIThe logarithm of the mass estimate for VI limit solution (hybrid_log_mass_vi)log(solMass)phys.massfloatE(B-V)HVIThe E(B-V) estimate for VI limit solution (hybrid_ebv_vi)magphot.color.excessfloatJ/MNRAS/520/63/ngc1433New hybrid SED age solutions ages, masses and reddenings for cluster class 1 and 2 in NGC 1433recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDID number from compact cluster catalog (ID_PHANGS_CLUSTERS_V0_9_1)meta.id;meta.mainintXposX coordinate (PHANGS_X)pixpos.cartesian.x;instr.detdoubleYposY coordinate (PHANGS_Y)pixpos.cartesian.y;instr.detdoubleRAJ2000Right ascension from PHANGS-HST (J2000) (PHANGS_RA)degpos.eq.ra;meta.mainDEJ2000Declination from PHANGS-HST (J2000) (PHANGS_DEC)degpos.eq.dec;meta.mainCIConcentration Index CI as difference magnitude between a vega magnitude in 1 pixel radius minus a vega magnitude in 3 pixel radius (PHANGS_CI)magphot.mag;arith.diff;em.optfloatlogAgeTThe original version 1 of logarithm age estimate with as described in Turner et al. 2021MNRAS.502.1366T (log_PHANGS_AGE_MINCHISQ)log(yr)meta.version;time.agedoublelogM*oOriginal logarithm of mass estimated with Chi2 minimization (log_PHANGS_MASS_MINCHISQ)log(solMass)phys.massfloatE(B-V)The original E(B-V) estimated with Chi2 minimization (PHANGS_EBV_MINCHISQ)magphot.color.excessfloatChiThe reduced phangs chi-sqr value (PHANGS_REDUCED_MINCHISQ)stat.fit.chi2doubleClassThe human cluster classification symmetric as 1 and asymmetric as 2 (PHANGS_CLUSTER_CLASS)meta.code.classfloatU-B? F336W - F438W vega system color magnitude where objects out of field of view, or with negative flux = EMPTY flux (u-b)magphot.color;em.opt.U;em.opt.BdoublenullableB-VF438W - F555W vega system color magnitude (b-v)magphot.color;em.opt.B;em.opt.VdoubleV-IF555W - F814W vega system color magnitude (v-i)magphot.color;em.opt.V;em.opt.IdoubleF555WmagThe F555W total magnitude in vega system (PHANGS_F555W_VEGA_TOT)magphot.mag;em.opt.VdoubleFHaThe Halpha flux estimate where objects out of the Field of View are set to 0 value (HA6562_FLUX)1e-18mW.m**-2.pixel**-1phot.flux;em.line.HalphadoubleICOThe molecular CO (2-1) flux intensity where objects out of the Field of View are set to 1.0E20 value (CO_intensity)K.km/sphot.flux.density;em.line.CO;em.mm.200-400GHzdoublelogAgeHOThe logarithm of the age estimate for Old Globular Cluster=OGC box solution (hybrid_log_age_ogc)log(yr)time.agedoublelogM*HOThe logarithm of the mass estimate for Old Globular Cluster = OGC box solution (hybrid_log_mass_ogc)log(solMass)phys.massfloatE(B-V)HOThe E(B-V) estimate Old Globular Cluster = OGC box solution (hybrid_ebv_ogc)magphot.color.excessfloatlogAgeHVIThe logarithm of the age estimate for VI limit solution (hybrid_log_age_vi)log(yr)time.agedoublelogMHVIThe logarithm of the mass estimate for VI limit solution (hybrid_log_mass_vi)log(solMass)phys.massfloatE(B-V)HVIThe E(B-V) estimate for VI limit solution (hybrid_ebv_vi)magphot.color.excessfloatJ/MNRAS/520/63/ngc3351New hybrid SED age solutions ages, masses and reddenings for cluster class 1 and 2 in NGC 3351B-VF438W - F555W vega system color magnitude (b-v)magphot.color;em.opt.B;em.opt.VdoubleV-IF555W - F814W vega system color magnitude (v-i)magphot.color;em.opt.V;em.opt.IdoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDID number from compact cluster catalog (ID_PHANGS_CLUSTERS_V0_9_1)meta.id;meta.mainintXposX coordinate (PHANGS_X)pixpos.cartesian.x;instr.detdoubleYposY coordinate (PHANGS_Y)pixpos.cartesian.y;instr.detdoubleRAJ2000Right ascension from PHANGS-HST (J2000) (PHANGS_RA)degpos.eq.ra;meta.mainDEJ2000Declination from PHANGS-HST (J2000) (PHANGS_DEC)degpos.eq.dec;meta.mainCIConcentration Index CI as difference magnitude between a vega magnitude in 1 pixel radius minus a vega magnitude in 3 pixel radius (PHANGS_CI)magphot.mag;arith.diff;em.optfloatlogAgeTThe original version 1 of logarithm age estimate with as described in Turner et al. 2021MNRAS.502.1366T (log_PHANGS_AGE_MINCHISQ)log(yr)meta.version;time.agedoublelogM*oOriginal logarithm of mass estimated with Chi2 minimization (log_PHANGS_MASS_MINCHISQ)log(solMass)phys.massfloatE(B-V)The original E(B-V) estimated with Chi2 minimization (PHANGS_EBV_MINCHISQ)magphot.color.excessfloatChiThe reduced phangs chi-sqr value (PHANGS_REDUCED_MINCHISQ)stat.fit.chi2doubleClassThe human cluster classification symmetric as 1 and asymmetric as 2 (PHANGS_CLUSTER_CLASS)meta.code.classfloatU-B? F336W - F438W vega system color magnitude where objects out of field of view, or with negative flux = EMPTY flux (u-b)magphot.color;em.opt.U;em.opt.BdoublenullableF555WmagThe F555W total magnitude in vega system (PHANGS_F555W_VEGA_TOT)magphot.mag;em.opt.VdoubleFHaThe Halpha flux estimate where objects out of the Field of View are set to 0 value (HA6562_FLUX)1e-18mW.m**-2.pixel**-1phot.flux;em.line.HalphadoubleICOThe molecular CO (2-1) flux intensity where objects out of the Field of View are set to 1.0E20 value (CO_intensity)K.km/sphot.flux.density;em.line.CO;em.mm.200-400GHzdoublelogAgeHOThe logarithm of the age estimate for Old Globular Cluster=OGC box solution (hybrid_log_age_ogc)log(yr)time.agedoublelogM*HOThe logarithm of the mass estimate for Old Globular Cluster = OGC box solution (hybrid_log_mass_ogc)log(solMass)phys.massfloatE(B-V)HOThe E(B-V) estimate Old Globular Cluster = OGC box solution (hybrid_ebv_ogc)magphot.color.excessfloatlogAgeHVIThe logarithm of the age estimate for VI limit solution (hybrid_log_age_vi)log(yr)time.agedoublelogMHVIThe logarithm of the mass estimate for VI limit solution (hybrid_log_mass_vi)log(solMass)phys.massfloatE(B-V)HVIThe E(B-V) estimate for VI limit solution (hybrid_ebv_vi)magphot.color.excessfloatJ/MNRAS/520/63/ngc1365New hybrid SED age solutions ages, masses and reddenings for cluster class 1 and 2 in NGC 1365recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDID number from compact cluster catalog (ID_PHANGS_CLUSTERS_V1P2)meta.id;meta.mainintXposX coordinate (PHANGS_X)pixpos.cartesian.x;instr.detdoubleYposY coordinate (PHANGS_Y)pixpos.cartesian.y;instr.detdoubleRAJ2000Right ascension from PHANGS-HST (J2000) (PHANGS_RA)degpos.eq.ra;meta.mainDEJ2000Declination from PHANGS-HST (J2000) (PHANGS_DEC)degpos.eq.dec;meta.mainCIConcentration Index CI as difference magnitude between a vega magnitude in 1 pixel radius minus a vega magnitude in 3 pixel radius (PHANGS_CI)magphot.mag;arith.diff;em.optfloatlogAgeTThe original version 1 of logarithm age estimate with as described in Turner et al. 2021MNRAS.502.1366T (log_PHANGS_AGE_MINCHISQ)log(yr)meta.version;time.agedoublelogM*oOriginal logarithm of mass estimated with Chi2 minimization (log_PHANGS_MASS_MINCHISQ)log(solMass)phys.massfloatE(B-V)The original E(B-V) estimated with Chi2 minimization (PHANGS_EBV_MINCHISQ)magphot.color.excessfloatClassThe human cluster classification symmetric as 1 for 366 occurences and asymmetric as 2 for 269 occurences (PHANGS_CLUSTER_CLASS)meta.code.classfloatU-B? F336W - F438W vega system color magnitude where objects out of field of view, or with negative flux = EMPTY flux (u-b)magphot.color;em.opt.U;em.opt.BdoublenullableB-VF438W - F555W vega system color magnitude (b-v)magphot.color;em.opt.B;em.opt.VdoubleV-IF555W - F814W vega system color magnitude (v-i)magphot.color;em.opt.V;em.opt.IdoubleF555WmagThe F555W total magnitude in vega system (PHANGS_F555W_VEGA_TOT)magphot.mag;em.opt.VdoubleFHaThe Halpha flux estimate where objects out of the Field of View are set to 0 value (HA6562_FLUX)1e-18mW.m**-2.pixel**-1phot.flux;em.line.HalphadoubleICOThe molecular CO (2-1) flux intensity where objects out of the Field of View are set to 1.0E20 value (CO_intensity)K.km/sphot.flux.density;em.line.CO;em.mm.200-400GHzdoublelogAgeHhiThe logarithm of the age estimate for high reddening solution (hybrid_log_age_high_red)log(yr)time.agedoublelogM*HhiThe logarithm of the mass estimate for high reddening solution (hybrid_log_mass_high_red)log(solMass)phys.massfloatE(B-V)HhiE(B-V) estimate for high reddening solution (hybrid_ebv_high_red)magphot.color.excessfloat