The Stellar and Gaseous Kinematics in NGC 253

This paper presents observations with intermediate spectral and spatialresolution along the major and minor axes of the starburst galaxy NGC 253. Thespectral ranges analyzed are in the region of the stellar MgIb (5175 A), thenear IR CaII triplet (8550 A) absorption features, and the region of the Halphaemission line. We have compared the shape of the stellar features with those ofreference stars and determined the line-of-sight velocity distribution (LOSVD)of the stellar component by using a two-dimensional Gaussian decompositionalgorithm, and show for the first time the rotation curve of the stellarcomponent in NGC 253. Comparing the recesion velocity curves of the gas andstars, it is seen that the stellar component has a decoupled kinematics respectto the gas, displaying a shollower velocity gradient and larger velocitydispersion that the gas in the inner regions. The minor axis kinematicstogether with the kinematics across the central 40$''$ along the major axis,suggest the presence of a rotating body with a kinematically misaligned axisrespect to the main disk of the galaxy. The asymmetries in the LOSVD along theminor axis together with the steep velocity gradient of the gaseous componentsuggest a merger scenario to explain the these kinematically signatures. Theenclosed mass in the central regions is computed to be (2.4+-0.5) 10^7$ Mo fora radius of r=0.7'' (10 pc). A double gaseous component in the central 6arcsecs is detected from the [SIII] lambda 9069 A data along the minor axis;this seems to be the signature of a superbubble due to a supernova rate of 0.05yr^{-1}.Comment: 17 pages latex, 13 encapsulated postscript figures. ApJ accepte