新发现的南半球含Gaia超快星系团的第一空间和运动学分析
First space and kinematical analysis of newly discovered southern UFMGs clusters with Gaia
摘要：
利用最近在南方发现的疏散星团的Gaia DR 2天体测量数据，对很少研究的NGC 5999附近（1.3度半径）的UFMG 1、UFMG 2和UFMG 3进行了运动学参数和空间形状结构的研究。用AD图方法分别计算了这些星团约107、168、98和154个成员的顶点位置，我们计算的顶点坐标值如下：（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）和（98.65 +/- 1.12 & -0.26 +/- 0.060; UFMG 3）。另一方面，还计算了这些的速度椭球参数VEP;例如，由于银河系坐标的空间速度，由于所有ij的矩阵元素的色散速度（sigma_1，sigma_2，sigma_3），平面圆盘上的投影距离（X_sun，Y_sun，Z_sun）以及太阳元素（S_sun，l_A，b_A）。根据空间和运动学形状的近似，UFMG和NGC 5999在空间位置上似乎有空间差异，但它们似乎形成于银河系圆盘的同一区域。总累积质量MC;包括主序NMS和非主序Nnon-MS的总数，并利用质光关系的二阶多项式进行计算，得到星团潮汐半径pc。最后，我们得出结论，NGC 5999，UFMG 1和UFMG 2是动态弛豫的（即τ>> 1），而第四个是非弛豫的。
英文摘要：
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.
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