# Characterizing dynamical stages of open clusters located in the Sagittarius spiral arm

## TL;DR

This study characterizes 12 open clusters in the Sagittarius arm, analyzing their dynamical stages using photometry and astrometry, revealing correlations between dynamical evolution and star loss.

## Contribution

It provides a detailed dynamical characterization of multiple open clusters using combined photometric and astrometric data, highlighting their evolutionary stages.

## Key findings

- More evolved clusters show greater low-mass star loss.
- Dynamical stages are linked to structural parameters like radius ratios and concentration.
- Clusters are relatively young and located along the Sagittarius spiral arm.

## Abstract

The study of dynamical properties of Galactic open clusters is a fundamental prerequisite for the comprehension of their dissolution processes. In this work, we characterized 12 open clusters, namely: Collinder 258, NGC 6756, Czernik 37, NGC 5381, Ruprecht 111, Ruprecht 102, NGC 6249, Basel 5, Ruprecht 97, Trumpler 25, ESO 129-SC32 and BH 150, projected against dense stellar fields. In order to do that, we employed Washington $CT_{1}$ photometry and GAIA DR2 astrometry, combined with a decontamination algorithm applied to the three-dimensional astrometric space of proper motions and parallaxes. From the derived membership likelihoods, we built decontaminated colour-magnitude diagrams, while structural parameters were obtained from King profiles fitting. Our analysis revealed that they are relatively young open clusters (log($t$ yr$^{-1}$) $\sim7.3-8.6$), placed along the Sagittarius spiral arm, and at different internal dynamical stages. We found that the half-light radius to Jacobi radius ratio, the concentration parameter and the age to relaxation time ratio describe satisfactorily their different stages of dynamical evolution. Those relative more dynamically evolved open clusters have apparently experienced more important low-mass star loss.