J/A+A/706/A87ivo://CDS.VizieR/J/A+A/706/A87doi:10.26093/cds/vizier/bc-p2/lihCDSLengen B.Anderson I.R.Cruz Reyes M.Viviani G.2026-03-02T20:01:23Z2026-02-03T09:38:39ZCDS support team

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

cds-question@unistra.frglobular-star-clustersvariable-starspopulation-ii-starsRecent work has established large samples of astrometrically confirmed RR Lyrae and type-II Cepheid members of Galactic globular clusters (GCs). Any given GC can contain multiple such stars at once, notably RR Lyrae stars pulsating in the fundamental mode (RRab) or the first overtone (RRc), and type-II Cepheids (T2Cep) of BL Her and W Vir types. Here, we present the first joint calibration of the Leavitt laws (LL) exhibited by 802 RRab, 345 RRc, and 21 T2Cep stars anchored to trigonometric parallaxes. Using the third data release of the ESA Gaia mission (GDR3), we have calibrated the intercepts of the RRab and RRc Leavitt laws in the reddening-free Gaia Wesenheit magnitude, MWG, to better than 1.0% in distance, and that of T2Cep to 1.3%, using a global fit to all data. The absolute scale is set by 37 nearby GCs with high- accuracy parallaxes while 56 additional GCs provide constraints on LL slopes as well as the LL intercept differences of RRc and T2Cep relative to RRab stars. Our global fit yields homogeneous high-accuracy distances of 93 GCs that show no evidence of bias for Gaia parallaxes of distant GCs. Control of systematics was demonstrated by 30 alternative fit variants, notably involving different treatments of metallicity effects, as well as by Markov Chain Monte Carlo analysis. Our results suggest that photometric metallicities of RR Lyrae stars require further improvements while also exhibiting possible signs of intra-cluster chemical inhomogeneity. This work lays the foundation for exploiting RRab, RRc, and T2Cep stars as high-accuracy standard candles for near-field cosmology and the extragalactic distance scale.2026A&A...706A..87Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/706/A87CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/684/A173 : RR Lyrae stars in Galactic Globular Clustershttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/706/A87https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/706/A87http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/706/A87https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/706/A87https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/706/A87http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/706/A87GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/706/A87/tablee2 (Anchor GCs used in the baseline fit)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/706/A87/tablee2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/706/A87/tablee2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/706/A87/tablee2?GETtext/xml+votable180.050000true6.0223292-72.08144440.005555555555555556Cone search capability for table J/A+A/706/A87/tablee3 (Host GCs used in the baseline fit)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/706/A87/tablee3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/706/A87/tablee3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/706/A87/tablee3?GETtext/xml+votable180.050000true48.0675417-55.21622220.0055555555555555566/6389 9436 9666 10008 10321 10336 12405 12425 12531 14489 16647 17121 19091 20001 21017 24843 25873 27237 27981 27986 28067 28705 28717 28741 28768-28769 28778 28815 28838 28867 28889 28959 28962 28970 28973-28974 29195 29202 29216 29222 29231 29233 29248 29318 29377 29632 29870 30323 30769 30998 31019 31043 31095 31115 31128 31398 31417 33321 33330 33635 34242 37294 38465 39642 41011 41257 41304 41522 41847 42314 42361 42700 42761 42841 42862 42955 42958 42990 43125 43193 43227 44086 44427 47125 47620 47825 47903 47935 47971 48035 48434 48698 48952https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/706/A87?format=asciidefaultJ/A+A/706/A87/tablee2Anchor GCs used in the baseline fitrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGCCluster namemeta.id;meta.maincharNstarsNumber of member stars used to determine the cluster parallaxmeta.numberintNRRabNumber of RRab stars belonging to the cluster used in the baseline fitmeta.numberintSimbadNameSimbad column added by the CDSmeta.idcharnullableNRRcNumber of RRc stars belonging to the cluster used in the baseline fitmeta.numberintNT2CepNumber of T2Cep stars belonging to the cluster used in the baseline fitmeta.numberintmufitDistance modulus determined by the baseline fitmagphot.mag.distModdoublee_mufitUncertainty in the distance modulus determined by the baseline fitmagstat.errordoublemuBV21Distance modulus from Baumgardt & Vasiliev (2021MNRAS.505.5957B)magphot.mag.distModdoublee_muBV21Uncertainty in the distance modulus from Baumgardt & Vasiliev (2021MNRAS.505.5957B)magstat.errordoubleplxfitParallax determined by the baseline fituarcsecpos.parallaxdoublee_plxfitUncertainty in the parallax determined by the baseline fituarcsecstat.errordoubleplxgaiaGC mean parallax from Cruz Reyes et al. (2024A&A...684A.173C, Cat. J/A+A/684/A173)uarcsecpos.parallax.trigdoublee_plxgaiaUncertainty in the GC mean parallax from Cruz Reyes et al. (2024A&A...684A.173C, Cat. J/A+A/684/A173)uarcsecstat.errordouble_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/A+A/706/A87/tablee3Host GCs used in the baseline fitSimbadNameSimbad column added by the CDSmeta.idcharnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGCCluster namemeta.id;meta.maincharNstarsNumber of member stars used to determine the cluster parallaxmeta.numberintNRRabNumber of RRab stars belonging to the cluster used in the baseline fitmeta.numberintNRRcNumber of RRc stars belonging to the cluster used in the baseline fitmeta.numberintNT2CepNumber of T2Cep stars belonging to the cluster used in the baseline fitmeta.numberintmufitDistance modulus determined by the baseline fitmagphot.mag.distModdoublee_mufitUncertainty in the distance modulus determined by the baseline fitmagstat.errordoublemuBV21Distance modulus from Baumgardt & Vasiliev (2021MNRAS.505.5957B)magphot.mag.distModdoublee_muBV21Uncertainty in the distance modulus from Baumgardt & Vasiliev (2021MNRAS.505.5957B)magstat.errordoubleplxfitParallax determined by the baseline fituarcsecpos.parallaxdoublee_plxfitUncertainty in the parallax determined by the baseline fituarcsecstat.errordoubleplxgaiaGC mean parallax from Cruz Reyes et al. (2024A&A...684A.173C, Cat. J/A+A/684/A173)uarcsecpos.parallax.trigdoublee_plxgaiaUncertainty in the GC mean parallax from Cruz Reyes et al. (2024A&A...684A.173C, Cat. J/A+A/684/A173)uarcsecstat.errordouble