OCCASO II. Physical parameters and Fe abundances of Red Clump stars in 18 Open Clusters

TL;DR

This paper presents high-resolution spectroscopic data and analysis of 115 Red Clump stars in 18 Open Clusters to study their chemical properties and implications for Galactic disk evolution.

Contribution

It provides a homogeneous analysis of Fe abundances and atmospheric parameters for Red Clump stars across multiple clusters using two methods, with a detailed comparison and validation.

Findings

Consistent Fe abundances obtained from two analysis methods.

Oldest clusters align with chemo-dynamical models when dynamical effects are included.

Validated membership of stars through radial velocities and abundances.

Abstract

Open Clusters have long been used to study the chemo-dynamical evolution of the Galactic disk. This requires an homogeneously analysed sample covering a wide range of ages and distances. In this aper we present the OCCASO second data release. This comprises a sample of high-resolution ($R>65,000$) and high signal-to-noise spectra of 115 Red Clump stars in 18 Open Clusters. We derive atmospheric parameters ($T_{\mathrm{eff}}$, $\log g$, $\xi$), and [Fe/H] abundances using two analysis techniques: equivalent widths and spectral synthesis. A detailed comparison and a critical review of the results of the two methods are made. Both methods are carefully tested between them, with the \emph{Gaia} FGK Benchmark stars, and with an extensive sample of literature values. We perform a membership study using radial velocities and the resulting abundances. Finally, we compare our results with a chemo-dynamical model of the Milky Way thin disk concluding that the oldest Open Clusters are consistent with the models only when dynamical effects are taken into account.