THE STELLAR AND GASEOUS KINEMATICS IN NGC-253

This paper presents observations made at intermediate spectral and spa tial resolutions along the major and minor axes of the starburst galax y NGC 253. The spectral ranges analyzed are in the region of the stell ar Mg I b (similar to 5175 Angstrom) line, in the near-IR Ca II triple t (similar to 8550 Angstrom) absorption features, and in the region of the Hu emission line. We compare the shape of the stellar features wi th those of reference stars and determine the line-of-sight velocity d istribution of the stellar component by using a two-dimensional Gaussi an decomposition algorithm, and we show for the first time the rotatio n curve of the stellar component in NGC 253. Comparing the recession v elocity curves of the gas and stars, we show that the stellar componen t has a decoupled kinematics with respect to the gas, displaying a sha llower velocity gradient and larger velocity dispersion than the gas i n the inner regions. The minor-axis kinematics, together with the kine matics across the central 40 '' along the major axis, suggest the pres ence of a rotating body with a kinematically misaligned axis with resp ect to the main disk of the galaxy. The asymmetries in the LOS velocit y distribution along the minor axis, together with the steep velocity gradient of the gaseous component, suggest a merger scenario as the so urce of these kinematic signatures. The enclosed mass in the central r egions is computed to be (2.4 +/- 0.5) x 10(7) M. for a radius of r = 0.'' 7 (10 pc). A double gaseous component in the central 6 '' is dete cted from the [S III] lambda 9069 Angstrom data along the minor axis; this seems to be the signature of a superbubble, due to a supernova ra te of 0.05 yr(-1).