# NGC 6067: a young and massive open cluster with high metallicity

## TL;DR

NGC 6067 is a young, massive, high-metallicity open cluster that provides valuable insights into stellar evolution, with detailed spectroscopic analysis revealing its properties, chemical composition, and evolutionary status of its stellar population.

## Contribution

This study offers the first detailed spectroscopic analysis of NGC 6067, determining its fundamental parameters, chemical abundances, and testing stellar evolution models at high metallicity.

## Key findings

- NGC 6067 has a distance of 1.78 kpc and an age of 90 Ma.
- The cluster exhibits supersolar metallicity, [Fe/H]=+0.19.
- Presence of a Li-rich red giant and enhanced s-process element Ba.

## Abstract

NGC 6067 is a young open cluster hosting the largest population of evolved stars among known Milky Way clusters in the 50-150 Ma age range. It thus represents the best laboratory in our Galaxy to constrain the evolutionary tracks of 5-7 M$_{\odot}$ stars. We have used high-resolution spectra of a large sample of bright cluster members (45), combined with archival photometry, to obtain accurate parameters for the cluster as well as stellar atmospheric parameters. We derive a distance of 1.78$\pm$0.12 kpc, an age of 90$\pm$20 Ma and a tidal radius of 14.8$^{6.8}_{3.2}$ arcmin. We estimate an initial mass above 5700 M$_{\odot}$, for a present-day evolved population of two Cepheids, two A supergiants and 12 red giants with masses $\approx$6 M$_{\odot}$. We also determine chemical abundances of Li, O, Na, Mg, Si, Ca, Ti, Ni, Rb, Y and Ba for the red clump stars. We find a supersolar metallicity, [Fe/H]=+0.19$\pm$0.05, and a homogeneus chemical composition, consistent with the Galactic metallicity gradient. The presence of a Li-rich red giant, star 276 with A(Li)=2.41, is also detected. An over-abundance of Ba is found, supporting the enhanced $s$-process. The ratio of yellow to red giants is much smaller than one, in agreement with models with moderate overshooting, but the properties of the cluster Cepheids do not seem consistent with current Padova models for supersolar metallicity.