1998A&A...335..894V

The averaged radius and velocity respectively associated to global potential and kinetic energies, are computed for spiral galaxies. Such dynamical parameters (effective radius and velocity) can be directly related to observational ones, being R_eff≃R_lim and V_eff≃v_ω,lim, where R_lim is either the R₂₅ radius or the last observed point of the rotation curve of the galaxy and v_ω,lim is its rotational velocity at this radius. It is proposed that the angular momentum can be replaced by the action, A=M R_eff V_eff, in the study of dynamical characterization of spiral galaxies (see, for instance, the analysis of Campos-Aguilar et al. (1993A&A...276...16C)).