The Open Cluster Chemical Abundances and Mapping Survey. VIII. Galactic Chemical Gradient and Azimuthal Analysis from SDSS/MWM DR19

Abstract The Open Cluster Chemical Abundances and Mapping (OCCAM) survey seeks to curate a large, comprehensive, uniform dataset of open clusters and member stars to constrain key Galactic parameters. This eighth entry from the OCCAM survey, based on the newly released Sloan Digital Sky Survey V/Milky Way Mapper Data Release 19 (DR19), has established a sample of 158 quality open clusters that are used to constrain the radial and azimuthal gradients of the Milky Way. The DR19 cluster sample [Fe/H] abundances are largely consistent with measurements from other large-scale spectroscopic surveys. However, the gradients we calculate deviate considerably for some elements. We find an overall linear Galactic radial [Fe/H] gradient of −0.079 ± 0.006 dex kpc −1 using the cluster’s current Galactocentric radius and a gradient of −0.071 ± 0.005 dex kpc −1 with respect to the cluster’s guiding center radius. We do not find strong evidence for significant evolution of the differential element gradients ([X/Fe]) investigated here (O, Mg, Si, S, Ca, Ti, Cr, Mn, Co, Ni, Na, Al, K, Ce, Nd), and instead show indications that the radial [Fe/H] gradient does not change significantly with stellar population age. For the first time, using the OCCAM sample, we have sufficient numbers of clusters to investigate Galactic azimuthal variations. In this work, we find evidence of azimuthal variations in the measured radial abundance gradient in the Galactic disk using our open cluster sample.