Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2507.15122

Stellar Population Astrophysics (SPA) with the TNG: NLTE atmospheric parameters and abundances of giant stars in 33 Open Clusters

M. Dal Ponte·V. D'Orazi·A. Bragaglia·A. R. Casey·N. Storm·L. Spina·J. Alonso-Santiago·G. Andreuzzi·A. Frasca·J. Kos·S. Lucatello·D. Romano·A. Vallenari·N. Vernekar
View original source ↗Read source document ↗Export metadata ↓

Abstract

Open clusters serve as important tools for accurately studying the chemical evolution of the Milky Way. By combining precise chemical data from high-resolution spectra with information on their distances and ages, we can effectively uncover the processes that have shaped our Galaxy. This study aims to derive NLTE atmospheric parameters and chemical abundances for approximately one hundred giant stars across 33 open clusters with near-solar metallicity. The clusters span a wide range of ages, enabling an assessment of the presence and extent of any age-related abundance gradients. In the Stellar Population Astrophysics (SPA) project, we acquired new high-resolution spectra of open clusters using the HARPS-N echelle spectrograph at the Telescopio Nazionale Galileo. We chemically characterized nine open clusters for the first time and reanalyzed previously studied SPA clusters, resulting in a consistent and homogeneous sample. We determined NLTE atmospheric parameters using the equivalent width method and derived NLTE chemical abundances through spectral synthesis for various elements, including alpha elements (Mg, Si, and Ti), light odd-Z elements (Na, Al), iron-peak elements (Mn, Co, and Ni), and neutron-capture elements (Sr, Y, and Eu). Our findings are compared with the existing literature, revealing good agreement. We examine the trends of [X/Fe] versus age, confirming previous observations and the enrichment patterns predicted by nucleosynthesis processes. Positive correlations with age are present for Mg, Si, Ti, Al, Mn, Co, Ni, and Sr, while Na and Y and Eu show a negative trend. This study emphasizes the significance of NLTE corrections and reinforces the utility of open clusters as tracers of Galactic chemical evolution. Furthermore, we provide a benchmark sample of NLTE abundances for upcoming open cluster surveys within large-scale projects such as 4MOST and WEAVE.

Explore related subjects

astro-ph.SRastro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M. Dal Ponte, V. D'Orazi, A. Bragaglia, A. R. Casey, N. Storm, L. Spina, J. Alonso-Santiago, G. Andreuzzi, A. Frasca, J. Kos, S. Lucatello, D. Romano, A. Vallenari, N. Vernekar. 2025-07-20. Stellar Population Astrophysics (SPA) with the TNG: NLTE atmospheric parameters and abundances of giant stars in 33 Open Clusters. https://doi.org/10.1051/0004-6361%2F202554258

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Good things always come in 3s: trimodality in the binary black-hole chirp-mass distribution supports bimodal black-hole formation

The latest GWTC-4 release from the LIGO-Virgo-KAGRA (LVK) collaboration nearly doubles the known population of double compact object mergers and reveals a new trimodal structure in the chirp-mass distribution of merging binary black holes (BBHs) below 30 Msun. Recent detailed stellar evolution models show that features in the pre-collapse cores of massive stars produce a bimodal black hole (BH) mass distribution, which naturally extends to a trimodal BBH chirp-mass distribution. Both distributions depend only weakly on metallicity, implying universal structural features which can be tested with LVK observations. Using a new compact-remnant mass prescription derived from these models, we perform rapid population synthesis simulations to test the robustness of the predicted chirp-mass structure against uncertainties in binary evolution and cosmic star formation history, and compare these results with the current observational data. The trimodal chirp-mass distribution emerges as a robust outcome of the new remnant-mass model, persisting across variations in binary and cosmic physics. In contrast, traditional BH formation models lacking a bimodal BH mass spectrum fail to reproduce the observed trimodality. The updated models also predict lower BBH merger rates by a factor of a few, in closer agreement with LVK constraints. Intriguingly, the central chirp-mass peak, dominated by unequal-mass BBHs, originates from a previously underappreciated formation pathway in which strong luminous blue variable winds suppress binary interaction before the first BH forms. If isolated binary evolution dominates BBH formation below 30 Msun, the relative heights of the three chirp-mass peaks offer powerful observational constraints on core collapse, BH formation, binary evolution, and cosmic star formation. These universal structural features may also serve as standard sirens for precision cosmology.

astro-ph.SR↗
arXiv2026

Simulating the convection in red super-giant stars: wobbling jets in common envelope evolution

We use our newly constructed three-dimensional red supergiant (RSG) stellar model, which also mimics nuclear energy production and photospheric emission, to calculate the stochastic component of the angular momentum of the mass that a companion spiraling within the RSG's envelope accretes during common envelope evolution (CEE). The accreted mass has a fixed-direction angular-momentum component arising from the density gradient in the RSG envelope and orbital motion. The angular momentum component with a stochastically varying direction results from vigorous envelope convection. We do not include the companion's influence on the RSG envelope during the CEE and consider an undisturbed, non-rotating RSG stellar model. We find that the fluctuating angular momentum amplitude can be several times the fixed-axis angular momentum. The total specific angular momentum of the accreted mass easily forms intermittent accretion disks around neutron stars and black holes, but it is only marginally sufficient, or not at all, to form accretion disks around main-sequence stellar companions. The intermittent accretion disks we expect to form will launch wobbling jets with varying axes. We discuss aspects of wobbling jets in the CEE and the grazing envelope evolution (GEE), which might precede the CEE or replace it altogether. Studies have claimed that jets are a crucial ingredient in many cases of CEE, and the standard CEE should include jets that the companion launches, before (like the GEE), during, and/or at the exit from the CEE. Our study supports this claim and emphasizes the importance of wobbling jets.

astro-ph.SR↗
arXiv2026

Central stars of newly discovered infrared nebulae: eruptive Be stars PY Gem and HD253659

The presence of a nebula around massive hot stars often works as an indicator that the object is either in an advanced evolutionary stage or a rare product of close binary interaction. Here, we focus on two Be stars - PY Gem and HD253659 - whose nebulae were detected with the Wide-field Infrared Survey Explorer. We estimated their basic physical parameters from modelling the spectral energy distribution and examined their variability. We combined archival photometric data from several ground-based survey telescopes and from the Transiting Exoplanet Survey Satellite (TESS) with our own data from dedicated multi-colour photometric and spectroscopic monitoring, and concluded that, despite having similar stellar properties, the photometric variability of the two objects is strikingly different. For HD253659 we detected continuous eruptive variability and a major outburst that took place between 2016 and 2022 along with numerous flicker events seen in the TESS data. HD253659 also exhibits loop-like behaviour in the colour-magnitude diagram, consistent with build-up and dissipation phases of a circumstellar disk seen close to pole-on. In contrast, during the past ~20 years PY Gem has lost its eruptive variability and shows only small-amplitude p and g-mode pulsations classifying PY Gem as βCephei hybrid pulsator. An incoherent low-frequency signal is identified as a Štefl frequency, which seems to be supported by the cyclic variation of the emission-line profiles. Detailed analysis of these stars indicates that both objects are inconsistent with evolved massive stars, and that the origin of their nebulae is more likely linked to the physics of the Be phenomenon.

astro-ph.SR↗