Chemical Abundance Gradients in Open Clusters from the Gaia/LAMOST Sample

Abstract

Based on a large and homogeneous sample of 299 open clusters (OCs) from Gaia DR3 and large sky area multiobject fiber spectroscopic telescope DR11, we studied the abundance gradients of the α -elements Mg and Si, and the iron-peak elements Fe and Ni to explore the chemical evolution of the Galactic disk. A noticeable downward trend in metallicities, with a slope of −0.048 ± 0.008 dex kpc ^−1 , is observed as the Galactocentric distance ( R _GC ) increases. The abundance gradients of both α -elements and iron-peak elements in our sample exhibit no apparent symmetry between the regions above and below the Galactic plane. The metallicities in the sample, scaled to the Galactocentric distance of the Sun, show an age-related increase of 0.017 ± 0.016 dex Gyr ^−1 . [El/H] exhibits distinct downward trends toward the outer Galaxy. In the inner Galaxy, younger OCs have lower [El/H] values than older clusters, whereas in the outer Galaxy, this trend is reversed. For OCs aged between 0.5 and 2.5 Gyr, the number of clusters migrating inward is approximately equal to those migrating outward. However, the outward migration distances are notably greater than the inward ones. Analyzing the impact of kinematic orbits on the radial and vertical abundance gradients of the four elements, we found that kinematic orbits exert minimal influence on the radial abundance gradients for both α -elements and iron-peak elements. In contrast, they have a pronounced effect on the vertical abundance gradients.

Keywords

• Galaxy abundances
• Galaxy evolution
• Open star clusters