arXiv subjects

Natalia Alvarez-Baena

Publications and source records attributed to Natalia Alvarez-Baena.

2 recordsLinked to original sources

arXiv2026

Stellar Population Astrophysics (SPA) with the TNG. Beyond the iron peak: Galactic evolution of molybdenum, ruthenium and zirconium through open clusters

Context: Open clusters serve as key laboratories for studying the chemical evolution of the Milky Way. In particular, leveraging these coeval groups of stars to study elements beyond the iron peak provides insights into heavy-element nucleosynthesis, whose origins remain uncertain. Aims: This work aims to determine the Mo, Ru, and Zr abundances for 81 stars across 30 open clusters. We compare these new chemical patterns with those of key reference elements (Y, Sr, Eu), which were previously derived by our group. This comparison seeks to disentangle the distinct contributions from various nucleosynthetic processes. Methods: Using the high-resolution spectra acquired within the Stellar Population Astrophysics programme using the HARPS-N echelle spectrograph at the Telescopio Nazionale Galileo, we estimate chemical abundances through spectral synthesis with TSFitPy under local thermodynamic equilibrium (LTE) conditions. Results: 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.

astro-ph.GA↗

arXiv2026

Stellar Population Astrophysics (SPA) with the TNG. CNO abundances in 28 open clusters

Aims. Our main aim with this work was to enlarge the pool of open clusters with determined carbon, nitrogen, and oxygen abundances in evolved giants to further advance chemical clocks in stellar age determinations. Methods. High-resolution spectra were analysed using a differential model atmosphere method. Carbon abundances were derived using spectral synthesis of the C2 band heads at 5135 and 5635.5 Å. The CN features at 6470-6490 Å were analysed to determine the abundances of nitrogen. The oxygen abundances were determined from the [O I] line at 6300 Å. Results. We provide abundances of C, N, and O for 88 giants in 28 open clusters and in two stars of the association Theia 1214. The results were compared with theoretical predictions and used for the analysis of the [C/N] relations with age, and we investigated the origin of the two Theia 1214 stars. Conclusions. Precise age dating requires separate age calibrations of [C/N] ratios for the first-ascent giants of the lower part of the red giant branch and for the red clump stars to account for the additional abundance alterations during the post-red giant branch luminosity bump evolution. In the first-ascent giant stars with larger turn-off masses, the observed C/N ratios are slightly higher than those predicted by standard models, and the obtained [C/N] versus age relation is flatter in the young age regime than in previous studies. We doubt that the two stars we investigated in the Theia 1214 association belong to the tail of NGC 752. Most probably, they are field stars.

astro-ph.SR↗