NUCLEAR-TO-DISK ROTATION CURVES OF GALAXIES IN THE H-ALPHA AND [N II]EMISSION-LINES

We have obtained optical CCD spectroscopy along the major axes of 22 n earby spiral galaxies of Sb and Sc types in order to analyze their rot ation curves. By subtracting the stellar continuum emission, we have o btained position-velocity (PV) diagrams of the H alpha and [N II] line s. We point out that the H alpha line is often superposed by a broad s tellar absorption feature (Balmer wing) in the nuclear regions, and, t herefore, the [N II] line is a better tracer of kinematics in the cent ral few hundred parsec regions. By applying the envelope-tracing techn ique to the H alpha and [N II] PV diagrams, we have derived nucleus-to -disk rotation curves of the observed galaxies. The rotation curves ri se steeply within the central few hundred parsecs, indicating a rapidl y rotating nuclear disk and mass concentration near the nucleus.