Kinematics of gas and stars in 20 disc galaxies

In this paper we present the kinematics of the gas and/or the stars of a sa mple of 20 disc galaxies. We investigate whether there is any relation betw een the kinematics of the gas and stars and the classical morphological typ e of the galaxies in the sample. We deduce that, in most of the late-type s pirals we have studied, the stars and the ionized gas are moving with virtu ally circular velocity, except when the spectroscopic slit crosses a bar re gion. On the other hand, we found in the central parts of early-type disc g alaxies a wider variety of different behaviour of stars and gas. We find ma ny possible factors that complicate the classification of the kinematical p roperties of the galaxies by their morphological type: the presence of coun ter-rotations (star vs. stars or star vs. gas), misalignment between the di fferent kinematic components present in the galaxy, the presence of a bar s tructure and its orientation with respect to the line of nodes of the galax y, and interactions and mergers or external accretion processes are some of the problems we find in the study of the kinematics of a galaxy.