J/A+A/710/A164ivo://CDS.VizieR/J/A+A/710/A164CDSFrasca A.Qin M.Alonso-Santiago J.Catanzaro G.Fu J.N.Zhang J.Y.,Bragaglia A.2026-06-10T08:11:40Z2026-06-10T09:02:46ZCDS support team

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

cds-question@unistra.fropen-star-clusterschemical-abundanceseffective-temperaturevisible-astronomyradial-velocitynarrow-band-photometryatomic-spectroscopyIn this work we present the results of our analysis of medium-resolution LAMOST spectra of candidate members of the cluster NGC 1647 with the aim of determining the stellar parameters, activity level, lithium abundance, and to study the cluster properties. We used the code ROTFIT to determine the atmospheric parameters (Teff, logg, and [Fe/H]), radial velocity (Vr), and projected rotation velocity (vsini). Moreover, for solar-type and cooler stars (Teff<6500K), we calculated the H-alpha and LiI-6708 net equivalent width by means of the subtraction of inactive photospheric templates. We determined the rotation periods for 160 stars by analyzing the available TESS photometry. We derived Vr, vsini, and atmospheric parameters for 341 spectra of 155 stars, plus three additional bright targets with archival UVES spectra. Moreover, we found four double-lined spectroscopic systems for which we provide the radial velocities of the two components. The Vr distribution of the cluster members peaks at -5.3km/s with a dispersion of 1.6km/s, while the average metallicity is [Fe/H]=-0.08+/-0.08dex, in line with previous determinations, which were based on only a handful stars. From the fitting of the spectral energy distribution of 160 likely members we infer the existence of a differential reddening across the cluster field with an average value of Av=1.1mag. The Av values show a distinct correlation with the color offset from the lower boundary of the main sequence, as observed in the Gaia color-magnitude diagram; conversely, this offset appears to be uncorrelated with vsini. These two findings confirm that differential reddening is the primary driver behind the observed extended Main-Sequence Turn-Off (eMSTO) in this cluster. The age of NGC 1647, obtained from the lithium abundance, is 203+/-27Myr, which is compatible with the values inferred from a gyrochronological approach and the isochrone fitting.2026A&A...710A.164Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/710/A164CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/618/A93 : Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)J/A+A/686/A42 : Improving the open cluster census. III. (Hunt+, 2024)J/A+A/594/A39 : LAMOST-Kepler parameters and activity indicatorsJ/A+A/664/A78 : Kepler targets class based on LAMOST spectra (Frasca+, 2022)J/A+A/698/A7 : Pleiades LAMOST mid-resolution observations (Frasca+, 2025)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/710/A164https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/710/A164http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/710/A164https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/710/A164https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/710/A164http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/710/A164GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/710/A164/table1 (Stellar parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/710/A164/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/710/A164/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/710/A164/table1?GETtext/xml+votable180.050000true71.3945219.328290.005555555555555556Cone search capability for table J/A+A/710/A164/table3 (Lithium equivalent width and abundance)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/710/A164/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/710/A164/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/710/A164/table3?GETtext/xml+votable180.050000true68.57130521.290688890.005555555555555556Cone search capability for table J/A+A/710/A164/tableb3 (Rotation periods from TESS photometry)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/710/A164/tableb3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/710/A164/tableb3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/710/A164/tableb3?GETtext/xml+votable180.050000true71.429931419.16650810.005555555555555556https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/710/A164?format=asciiOpticaldefaultJ/A+A/710/A164/table1Stellar parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMoreindicates data in other tablesmeta.ref.urlcharStarStar name (1)meta.idcharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainGaiaDR3Gaia DR3 source_id (source_id)meta.id;meta.mainprimaryTeffEffective temperatureKphys.temperature.effectiveinte_TeffEffective temperature errorKstat.error;phys.temperature.effectiveintloggLogarithm of surface gravitylog(cm.s**-2)phys.gravityfloate_loggError on logarithm of surface gravitylog(cm.s**-2)stat.errorfloat[Fe/H]Iron abundance relative to the Sunlog(Sun)phys.abund.Fefloate_[Fe/H]? Error on iron abund relative to the Sunlog(Sun)stat.error;phys.abund.Fefloatnullablel_vsiniLimit flag on vsinimeta.code.error;phys.veloc.rotatcharvsiniProjected rotational velocitykm/sphys.veloc.rotatfloate_vsini? Projected rotational velocity errorkm/sstat.error;phys.veloc.rotatfloatnullableSpTypeSpectral type in MK or HDsrc.spTypecharSampleSample (2)src.samplecharHRVAverage Heliocentric Radial Velocitykm/sspect.dopplerVeloc;pos.heliocentric;stat.meanfloate_HRVHeliocentric Radial Velocity errorkm/sstat.errorfloatRemarksRemarks (3)meta.notecharGDR3Display the Gaia DR3 data (I/355)meta.ref.urlcharJ/A+A/710/A164/table2Activity indicatorsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarLAMOST designation (JHHMMSS.ss+DDMMSS.s)meta.idcharGaiaDR3Gaia DR3 source_id (source_id)meta.id;meta.mainTeffEffective temperatureKphys.temperature.effectiveinte_TeffEffective temperature errorKstat.error;phys.temperature.effectiveintloggLogarithm of surface gravitylog(cm.s**-2)phys.gravityfloate_loggError on logarithm of surface gravitylog(cm.s**-2)stat.errorfloatl_EWHaLimit flag on H{alpha} equivalent widthmeta.code.errorcharEWHaH{alpha} equivalent width0.1nmspect.line.eqWidthfloate_EWHaH{alpha} equivalent width error0.1nmstat.errorfloatFHaH{alpha} flux (in erg/cm2/s)mW.m**-2phot.flux;em.line.Halphadoublee_FHaH{alpha} flux error (in erg/cm2/s)mW.m**-2stat.errordoublelogRHalogarithm of Luminosity ratio H{alpha}/Bolometric log(L_H{alpha}_/L_bol_)phys.luminosity;arith.ratiofloate_logRHaError of log(L_H{alpha}_/L_bol_)stat.errorfloatSampleSample (1)src.samplecharJ/A+A/710/A164/table3Lithium equivalent width and abundanceEW(Li)Lithium equivalent width0.1pmspect.line.eqWidthinte_EW(Li)rms uncertainty on EW(Li)0.1pmstat.errorintA(Li)Lithium abundancephys.abundfloate_A(Li)Error on A(Li)stat.errorfloatSampleSample (1)src.samplecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarLAMOST designation (JHHMMSS.ss+DDMMSS.s)meta.idcharGaiaDR3Gaia DR3 source_id (source_id)meta.id;meta.mainRAJ2000Right Ascention (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainTeffEffective temperatureKphys.temperature.effectiveinte_TeffEffective temperature errorKstat.error;phys.temperature.effectiveintloggLogarithm of surface gravitylog(cm.s**-2)phys.gravityfloate_loggError on logarithm of surface gravitylog(cm.s**-2)stat.errorfloatJ/A+A/710/A164/tableb2Radius, luminostity, and extinction from the SEDsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar name (1)meta.idcharGaiaDR3Gaia DR3 source_id (source_id)meta.id;meta.mainTeffEffective temperatureKphys.temperature.effectiveinte_TeffEffective temperature errorKstat.error;phys.temperature.effectiveintRadRadiuslog(solRad)phys.size.radiusfloate_RadUncertainty on Radlog(solRad)stat.errorfloatLumLuminositylog(solLum)phys.luminositydoublee_LumUncertainty on Lumlog(solLum)stat.errorfloatAvV band extinctionlog(mag)phys.absorptionfloate_AvUncertainty on Avlog(mag)stat.errorfloatJ/A+A/710/A164/tableb3Rotation periods from TESS photometrySimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3Gaia DR3 source_id (source_id)meta.id;meta.mainTICTESS Input Catalog identifiermeta.idlongProtRotation perioddtime.periodfloate_ProtUncertainty on Protdstat.errorfloat_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.main