Radial abundance gradients of 18 elements in Galactic open clusters from infrared MWM spectra

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Context . Open clusters are powerful tools for studying the Milky Way. While large spectroscopic surveys now provide spectra for many cluster members, automated pipelines and heterogeneous membership selections can introduce systematics and inflate apparent cluster scatter. Therefore, a homogeneous reanalysis with careful membership control and an explicit treatment of departures from local thermodynamic equilibrium is valuable for establishing robust abundance gradients. Aims . The aim is to derive precise Galactic radial abundance gradients for multiple elements using open cluster giants and to investigate how these gradients depend on cluster age. Methods . We reanalyzed high-resolution infrared APOGEE Milky Way Mapper spectra from Data Release 19 (DR19) of the Sloan Digital Sky Survey for 655 open cluster members selected from Gaia data that satisfied strict quality cuts on the signal-to-noise ratio. Stellar parameters and 18 elemental abundances were obtained using spectrum fitting with the Python version of Spectroscopy Made Easy, applying nonlocal thermodynamic equilibrium corrections for several key atomic species. Further quality control of the results was made by visual inspection of all fitted synthetic spectra. Results . The metallicity of the clusters decreases with galactocentric radius, following a global slope close to –0.06 dex/kpc. Beyond 10–11 kpc, there is modest flattening. In addition to the elements analyzed in the Milky Way Mapper study, we derived open-cluster gradients for V, Cu, Zn, and Yb using APOGEE spectra. All elements exhibit negative [X/H] radial gradients of comparable magnitude, while [X/Fe] gradients are close to zero for the α and iron-peak groups. Several odd-Z and neutron capture species exhibit mild outward increases in [X/Fe], consistent with nucleosynthetic yields dependent on metallicity and/or delayed production channels for these elements. Old clusters have shallower gradients than young ones. However, the observed age dependence is influenced by the link between cluster age and galactocentric radius in the sample. Conclusions . Compared with the Milky Way Mapper study, the present reanalysis yields generally smaller reported per-cluster abundance uncertainties and suggests distinct, element-dependent revisions to the inferred Galactic trends. While the global gradients align closely with the optical Gaia-ESO results, we do not observe a straightforward flattening of the gradients with age. Our revised abundance scale reveals a shallower, broken radial metallicity gradient, providing a more robust observational benchmark for Galactic chemical-evolution models.