First space and kinematical analysis of newly discovered southern UFMGs clusters with Gaia

TL;DR

This study presents the first kinematical and spatial analysis of newly discovered southern open clusters UFMG 1, UFMG 2, and UFMG 3 using Gaia DR2 data, revealing their formation region and dynamical states.

Contribution

It provides the initial kinematic, spatial, and dynamical characterization of these clusters, including apex positions, velocity ellipsoids, and mass estimates, which were previously unstudied.

Findings

UFMG clusters likely formed in the same Galactic disc region.

UFMG 1, UFMG 2, and NGC 5999 are dynamically relaxed.

UFMG 3 is non-relaxed.

Abstract

The work on the kinematical parameters and spatial shape structure have been performed with Gaia DR2 astrometry data of the new recently southern discovered open clusters; UFMG 1, UFMG 2, and UFMG 3 in the vicinity (1.3 degrees radius) of the rarely studied NGC 5999. The apexes positions with AD-diagram method are computed for about 107, 168, 98, and 154 members of these star clusters, respectively, our calculated values of apex coordinates, seems like: (A, D) = (102.40 +/- 1.02 & -4.60 +/- 0.47; NGC 5999), (96.69 +/- 1.10 & -0.58 +/- 0.045; UFMG 1), (97.47 +/- 1.09 & 1.56 +/- 0.051; UFMG 2), and (98.65 +/- 1.12 & -0.26 +/- 0.060; UFMG 3). On the other hand, Velocity Ellipsoid Parameters VEPs for those are also computed; e.g. space velocities due to Galactic coordinates, dispersion velocities (sigma_1, sigma_2, sigma_3) due to matrix elements for all ij, projected distances (X_sun, Y_sun, Z_sun) on the plane disc, and the Solar elements (S_sun, l_A, b_A). According to an approximation of spatial and kinematical shape, UFMGs and NGC 5999 seem to have a spatial difference in their space locations but they appear to have formed in the same region of the Galactic disc. The total cumulative mass MC; including total number of main-sequence NMS and non-main-sequence Nnon-MS of these clusters also evaluated here with a second-order polynomial of mass-luminosity relation in order to get clusters tidal radii (pc). Finally, we concluded that NGC 5999, UFMG 1, and UFMG 2 are dynamically relaxed (i.e. tau >> 1), and the fourth one in non-relaxed.