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 } ) \sim 7.3 - 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 .