J/A+A/706/A225ivo://CDS.VizieR/J/A+A/706/A225CDSCatanzaro G.Bhardwaj A.Ripepi V.Trentin E.Marconi M.Romaniello M.,Matsunaga N.De Somma G.Sicignano T.Musella I.Luongo E.Testa V.,Soung-Chul Y.2026-03-02T06:25:50Z2026-02-10T10:40:42ZCDS support team

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

cds-question@unistra.frvariable-starschemical-abundancesClassical Cepheids are fundamental primary distance indicators and crucial tracers of the young stellar population in the Milky Way and nearby galaxies. While most chemical abundance studies of Cepheids have been carried out in the optical domain, near-infrared (NIR) spectroscopy offers unique advantages in terms of reduced extinction and access to new elemental tracers. Our goal is to validate NIR abundance determinations against well-established optical results and to explore the diagnostic power of previously unexplored NIR lines. NIR spectroscopy is far less hampered by interstellar extinction than optical observations, which allows us to probe Cepheids at larger distances and in highly obscured regions of the Galaxy. Moreover, the H and K bands provide access to diagnostic lines of elements (e.g., P, K, and Yb) that are not available in the optical domain. We acquired high-resolution (R~45000) spectra of 21 Galactic and 2 Large Magellanic Cloud (LMC) classical Cepheids with the high-resolution Immersion Grating Infrared Spectrometer (IGRINS) in the H and K bands. Effective temperatures were derived from a photometric approach and line-depth ratios, and the gravities and microturbulent velocities were estimated using empirical calibrations and statistical constraints. The abundances of 16 elements were determined through a full spectral synthesis in local thermodynamic equilibrium. We performed an extensive error analysis and compared our results with previous optical studies of the same stars. Our NIR abundances and the optical literature values agree very well ({DELTA}[Fe/H]<=0.02 dex and {sigma}=~0.07dex), which confirms the reliability of IGRINS-based measurements. The derived abundance gradients in the Galactic disk are fully consistent with previous optical determinations, with slopes of -0.06, -0.05, and -0.05dex/kpc for Fe, Mg, and Si, respectively. We provide homogeneous determinations of P, K, and Yb abundances from NIR lines for classical Cepheids for the first time, and we report trends that are consistent with Galactic chemical evolution models. Moreover, the two LMC Cepheids included in our sample that were previously analyzed in the optical provide a direct benchmark that confirms the accuracy of NIR abundance determinations in extragalactic metal-poor environments. Our study demonstrates that high-resolution NIR spectroscopy of Cepheids yields robust abundances that are fully compatible with optical results and provides access to additional elements of nucleosynthetic interest. These results pave the way for future large-scale NIR surveys of Cepheids with facilities such as MOONS, ELT, and JWST, which are crucial for tracing the chemical evolution of the Milky Way and nearby galaxies in heavily obscured regions.2026A&A...706A.225Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/706/A225CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/508/4047 : 47 classical Cepheids HARPSN@TNG spectroscopyJ/ApJ/913/38 : Compilation of Cepheids in the MW and MCs (Breuval+, 2021)J/A+A/681/A65 : Cepheids PL relation metallicity dependence (Trentin+, 2024)J/A+A/683/A234 : Cepheid Metallicity in the Leavitt Law SurveyJ/A+A/690/A246 : Cepheid radial abundance gradients (Trentin+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/706/A225https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/706/A225http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/706/A225https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/706/A225https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/706/A225http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/706/A225GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/706/A225/table4 (*LTE abundances [X/H] and uncertainties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/706/A225/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/706/A225/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/706/A225/table4?GETtext/xml+votable180.050000true155.34573-61.07409360.0055555555555555566/14409 23622 23852 29081 29095 29897 33076 33120 37223 37336 37340 37757 37931 38023 39771 39790 39889 39908 39933 41375 41461 42297 42820https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/706/A225?format=asciidefaultJ/A+A/706/A225/table3Spectral line list and atomic parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSpeciesChemical speciesmeta.notecharlambdaAir wavelength0.1nmem.wldoublen_lambda[*] * indicates blended linesmeta.notecharloggflog10(gf)phys.absorption.coefffloatEiLower excitation energyeVphys.atmol.excitation;stat.minfloatJiLower level total angular momentum Jphys.angMomentum;phys.atmol.levelfloatEfUpper excitation energyeVphys.atmol.excitation;stat.maxfloatJfUpper level total angular momentum Jphys.angMomentum;phys.atmol.levelfloatlogGR? log10(gamma_rad), radiative damping constantphys.atmol.damping;phys.atmolfloatnullablelogGS? log10(gamma_Stark), Stark damping constantphys.atmol.damping;phys.atmolfloatnullablelogGW? log10(gamma_vdW), Van der Waals damping constantphys.atmol.damping;phys.atmolfloatnullableJ/A+A/706/A225/table4*LTE abundances [X/H] and uncertaintiesSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDStar identifiermeta.id;meta.mainchar[C/H]Abundance [C/H]phys.abundfloate_[C/H]1-sigma uncertainty on [C/H]stat.error;phys.abundfloat[N/H]Abundance [N/H]phys.abundfloate_[N/H]1-sigma uncertainty on [N/H]stat.error;phys.abundfloat[Na/H]Abundance [Na/H]phys.abundfloate_[Na/H]1-sigma uncertainty on [Na/H]stat.error;phys.abundfloat[Mg/H]Abundance [Mg/H]phys.abundfloate_[Mg/H]1-sigma uncertainty on [Mg/H]stat.error;phys.abundfloat[Al/H]Abundance [Al/H]phys.abundfloate_[Al/H]1-sigma uncertainty on [Al/H]stat.error;phys.abundfloat[Si/H]Abundance [Si/H]phys.abundfloate_[Si/H]1-sigma uncertainty on [Si/H]stat.error;phys.abundfloat[P/H]Abundance [P/H]phys.abundfloate_[P/H]1-sigma uncertainty on [P/H]stat.error;phys.abundfloat[S/H]Abundance [S/H]phys.abundfloate_[S/H]1-sigma uncertainty on [S/H]stat.error;phys.abundfloat[K/H]Abundance [K/H]phys.abundfloate_[K/H]1-sigma uncertainty on [K/H]stat.error;phys.abundfloat[Ca/H]Abundance [Ca/H]phys.abundfloate_[Ca/H]1-sigma uncertainty on [Ca/H]stat.error;phys.abundfloat[Ti/H]Abundance [Ti/H]phys.abundfloate_[Ti/H]1-sigma uncertainty on [Ti/H]stat.error;phys.abundfloat[Mn/H]Abundance [Mn/H]phys.abundfloate_[Mn/H]1-sigma uncertainty on [Mn/H]stat.error;phys.abundfloat[Fe/H]Abundance [Fe/H]phys.abundfloate_[Fe/H]1-sigma uncertainty on [Fe/H]stat.error;phys.abund.Fefloat[Ni/H]Abundance [Ni/H]phys.abundfloate_[Ni/H]1-sigma uncertainty on [Ni/H]stat.error;phys.abundfloat[Ce/H]Abundance [Ce/H]phys.abundfloate_[Ce/H]1-sigma uncertainty on [Ce/H]stat.error;phys.abundfloat[Yb/H]Abundance [Yb/H]phys.abundfloate_[Yb/H]1-sigma uncertainty on [Yb/H]stat.error;phys.abundfloat_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