COMBINED STUDY OF THE SOLAR NEIGHBORHOOD KINEMATICS - SPHERICAL-HARMONICS AND TAYLOR EXPANSIONS

In this paper we relate two methods of analyzing the kinematic parameters of the local macroscopic motions of the Galaxy: (a) The Ogorodnikov-Milne model (OM) that consists in the three-dimensional Taylor expansion of the mean velocity field. (b) The two-dimensional spherical harmonic development of the velocity components (SH). We present the theoretical relations between the SH coefficients and the second-order OM ones for the radial velocity vrand the galactic heliocentric components of the velocity U, V, W. Only the hypothesis of separability of the stellar density function of the sample into angular and radial parts is needed. Also, we apply them to 4732 A-M stars included in the Figueras (1986) sample. © 1990 Kluwer Academic Publishers.