KINEMATICS OF THE IONIZED-GAS IN NGC-253

High resolution optical spectra acquired with the ESO New Technology Telescope+the ESO Multimode Instrument along the major axis of the barred Sc starburst galaxy NGC 253 give detailed information on the kinematics of the galaxy at different scales from the inner nuclear region up to distances of 10′. We find strong evidence for a nuclear ring about 20″ in diameter, with a circular velocity Vmax=110 km/s, which is possibly responsible for the gas supply to the nuclear starburst region of the galaxy. The analysis of the dynamics of the bar in NGC 253 indicates that the nuclear ring is related to the presence of an inner Lindblad resonance at ∼300 pc. In this framework, the observed velocities indicate a mass in the central 10″ of 3×108 script M sign⊙. Good agreement is obtained between the new optical data and published H I rotation curves at larger radii. © 1995 American Astronomical Society.