Speaker
Description
Open clusters (OCs) are gravitationally bound stellar systems with masses up to ∼10^4 M⊙ ranging from several hundreds to tens of thousands members, that share between them properties such as age, kinematics and initial chemical composition. This makes them powerful tracers of the chemical evolution of the Galactic disc, as their ages and distances can be precisely determined. As part of the Stellar Population Astrophysics (SPA) project, we analysed high-resolution spectra of 95 giant stars in 32 OCs obtained with the HARPS-N spectrograph at the Telescopio Nazionale Galileo (TNG).
We determined the Mo, Ru, and Zr abundances for 81 stars across 30 OCs through spectral synthesis with TSFitPy under LTE conditions. We compare these new chemical patterns with those of key reference elements (Y, Sr, Eu), which were previously derived by our group, aiming to disentangle the distinct contributions from various nucleosynthetic processes.
This study provides the first Ru abundances for a large open cluster sample, alongside new measurements for Mo and Zr. We observe tight correlations between Mo, Ru, and other s-process elements (Sr, Y, Zr), with slopes near unity, suggesting common enrichment timescales. Conversely, relations with the r-process element Eu show significant deviations, implying additional nucleosynthetic contributions. Crucially, chemical planes involving [Mo/Ru] and [s/Mo] ratios suggest systematic offsets when compared to theoretical s-process predictions.