Abstract
Based on space velocity components UVW and using a recent dataset for Castor and Ursa Major moving groups, we compute the apex position with two methods. Classical convergent procedures give (A(cp), D-cp) = (80.degrees 7830, -17.degrees 2598; Castor, 298.degrees 334, -34.degrees 6405; UMa) for Castor and Ursa Major groups. According to the AD-map method we deduce the apex position (A(0), D-0) = (79.degrees 5514, -17.degrees 3948; Castor, 304.degrees 767, -35.degrees 2045; UMa) for these two objects. These results are in good agreement with other published coordinated. Also, we calculate all parameters with a model of stream velocity ellipsoidal motions, which reveals inner kinematical structure. Finally, we consider the intrinsic variations considered with late-type moving groups (streams) for the longitude of the vertex versus temperature (spectral types).