The Hyades Kinematical Structure with Gaia Era

Abstract

In this work, we have improved the Hyades members with crossmatch between Hipparcos and the recent Gaia EDR3 source, the obtained members with highly probable are about 186 candidates. Considering the classical convergent point and depending on proper motions and radial velocities, we have computed the apex position (A_cp,D_cp )=(〖93〗^o.36±0^o.046,7^o.43±0^o.713) which is in line with others. The internal structural parameters of the Hyades open cluster are demonstrated here with space spatial velocities; i.e., (V ̅_X,V ̅_Y,V ̅_Z; km s^(-1) )=(-5.97±0.41, 45.54±6.75, 5.52±0.43) and (U ̅,V ̅,W ̅; km s^(-1) )= (-42.11±6.50, -19.09±4.37, -1.32±0.44) and on basis of matrix elements (μ_ij ), the Velocity Ellipsoid Parameters were achieved, e.g., (λ_1,λ_1,λ_1; km s^(-1) )=(2137.36 ± 23.12,6.06 ± 0.41,2.53 ± 0.63) and (σ_1,σ_1,σ_1; km s^(-1) )=(46.23 ± 6.80,2.47 ± 0.64,1.59 ± 0.80). For the observational quantities, we have deduced a correlation coefficient of about ≈0.83 for the kinematical property of proper motions on both sides (μ_α cos⁡δ,μ_δ; mas yr^(-1) ) and the physical property with the angular distances (λ) from the vertex, and those prove that the attributes are completely related linearly.