J/A+A/712/A150ivo://CDS.VizieR/J/A+A/712/A150CDSXiong J.Chen X.Li J.Cheng Q.Zhang X.Liu C.Han Z.Chen X.2026-08-13T08:14:40Z2026-08-13T09:13:58ZCDS support team

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

cds-question@unistra.frgiant-starsstellar-distancephotometryThe surface brightness-color relation (SBCR) links stellar color to angular diameter and is a key ingredient of geometric distance measurements on the first rung of the cosmic distance ladder. However, previous RGB-based calibrations were limited by small samples and did not observeably constrain the role of metallicity. We aim to quantify the metallicity dependence of the SBCR for red giant branch (RGB) stars and to test the robustness of the relation using asteroseismic radii, Gaia distances, and atmospheric parameters from APOGEE. We selected more than 2000 RGB stars from APOKASC-3 to calibrate and validate the SBCR. Johnson V magnitudes were synthesized from Gaia XP spectra and homogenized to widely used SBCR photometric systems, while Ks photometry was taken from 2MASS. Angular diameters derived from asteroseismic radii and Gaia distances (ARD) were used to construct the SBCR. We explored three fitting strategies: metallicity-free, metallicity-binned, and global metallicity-dependent relations. Over the range V-Ks, the SBCR shows only a weak metallicity dependence. A change of 1dex in [Fe/H] modifies the predicted angular diameter by less than 1%, well below the intrinsic scatter of the calibration (~0.05mag). This result is consistent with theoretical expectations. Comparison with the interferometric sample reveals a systematic offset of ~1.5% toward smaller angular diameters in our SBCR predictions, with a mild color dependence. The metallicity effect on the SBCR is small in the color range explored here, but it becomes relevant for sub-percent distance measurements. Our results show that large RGB samples with asteroseismic radii and Gaia distances provide a powerful observational route for SBCR calibration, with clear potential for extension to cooler and redder giants as the precision and parameter coverage of the input data improve.2026A&A...712A.150Xhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/712/A150CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/712/A150https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/712/A150http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/712/A150https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/712/A150https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/712/A150http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/712/A150GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/712/A150/fitsamp (Fitting sample, RGB stars used to calibrate the SBCRs)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/712/A150/fitsamp?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/712/A150/fitsamp?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/712/A150/fitsamp?GETtext/xml+votable180.050000true297.850189541.824580.005555555555555556Cone search capability for table J/A+A/712/A150/testsamp (Testing sample, independent RGB used to validate the derived relations)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/712/A150/testsamp?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/712/A150/testsamp?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/712/A150/testsamp?GETtext/xml+votable180.050000true288.158980545.486770.0055555555555555564/922-923 933-934 944-945 5/3645 3647 3683 3704 3706 3731 3740-3741 3784 3789 3792 6/14567 14573 14575 14577 14586-14587 14730-14731 14744 14746 14750-14751 14792 14794-14795 14822 14828 14830-14831 14915-14916 14918-14919 14923 14968-14969 14971-14973 15040-15042 15044-15045 15060-15062 15140-15142 15144 15146-15147 15150 15153 15155 15160 15172-15174 15178 15200 152328.650015785639275e-20 9.710690472292815e-20https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/712/A150?format=asciidefaultJ/A+A/712/A150/fitsampFitting sample, RGB stars used to calibrate the SBCRsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3Gaia DR3 source identifiermeta.id;meta.mainKICKepler Input Catalog identifiermeta.idintRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainEvolStateAsteroseismic evolutionary statesrc.classcharRadiusAsteroseismic stellar radiussolRadphys.angSize;srcfloate_RadiusUncertainty on RadiussolRadstat.error;phys.size.radiusfloat[Fe/H]Stellar metallicity [Fe/H]phys.abund.Zfloate_[Fe/H]Uncertainty on [Fe/H]stat.error;phys.abund.FefloatrgeoGaia geometric distance (Bailer-Jones et al., 2021, Cat. I/352)pcphys.angSize;srcdoubleb_rgeoLower confidence limit of rgeopcstat.fit.paramdoubleB_rgeoUpper confidence limit of rgeopcstat.fit.paramdoubleKmag2MASS Ks-band magnitudemagphot.mag;em.IR.Kfloate_KmagUncertainty on Kmagmagstat.error;phot.magfloatE(B-V)3dThree-dimensional reddening E(B-V)magphot.color.excessdoublee_E(B-V)3dUncertainty on E(B-V)magstat.errordoubleVmagXPJohnson V magnitude synthesized from Gaia XP spectra (corrected)magphot.mag;em.opt.Vdoublee_VmagXPUncertainty on Vmag_xpmagstat.errordoubleSvXPSurface brightness parameter S_Vphot.mag.sb;em.opt.VdoubleE_SvXPUpper uncertainty on S_Vstat.error;stat.maxdoublee_SvXPLower uncertainty on S_Vstat.errordouble(V-Ks)XPExtinction-corrected colour (V-Ks)_0_magphot.color.excessdoublee_(V-Ks)XPUncertainty on (V-Ks)_0_magstat.errordoubleLDLimb-darkened angular diameter (LD) derived from the ARD (Gaia distance + asteroseismic stellar radius) methodmasphys.angSizedoublee_LDUncertainty on LDmasstat.errordoubleSimbadSimbad column added by the CDSmeta.ref.urlcharJ/A+A/712/A150/testsampTesting sample, independent RGB used to validate the derived relationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3Gaia DR3 source identifiermeta.id;meta.mainKICKepler Input Catalog identifiermeta.idintRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainEvolStateAsteroseismic evolutionary statesrc.classcharRadiusAsteroseismic stellar radiussolRadphys.angSize;srcfloate_RadiusUncertainty on RadiussolRadstat.error;phys.size.radiusfloat[Fe/H]Stellar metallicity [Fe/H]phys.abund.Zfloate_[Fe/H]Uncertainty on [Fe/H]stat.error;phys.abund.FefloatrgeoGaia geometric distance (Bailer-Jones et al., 2021, Cat. I/352)pcphys.angSize;srcdoubleb_rgeoLower confidence limit of rgeopcstat.fit.paramdoubleB_rgeoUpper confidence limit of rgeopcstat.fit.paramdoubleKmag2MASS Ks-band magnitudemagphot.mag;em.IR.Kfloate_KmagUncertainty on Kmagmagstat.error;phot.magfloatE(B-V)3dThree-dimensional reddening E(B-V)magphot.color.excessdoublee_E(B-V)3dUncertainty on E(B-V)magstat.errordoubleVmagXPJohnson V magnitude synthesized from Gaia XP spectra (corrected)magphot.mag;em.opt.Vdoublee_VmagXPUncertainty on Vmag_xpmagstat.errordoubleSvXPSurface brightness parameter S_Vphot.mag.sb;em.opt.VdoubleE_SvXPUpper uncertainty on S_Vstat.error;stat.maxdoublee_SvXPLower uncertainty on S_Vstat.errordouble(V-Ks)XPExtinction-corrected colour (V-Ks)_0_magphot.color.excessdoublee_(V-Ks)XPUncertainty on (V-Ks)_0_magstat.errordoubleLDLimb-darkened angular diameter (LD) derived from the ARD (Gaia distance + asteroseismic stellar radius) methodmasphys.angSizedoublee_LDUncertainty on LDmasstat.errordoubleSimbadSimbad column added by the CDSmeta.ref.urlchar