Lindblad et al. 4 Fig. 3.— Fluxes and velocities over the central region of NGC 1358 along the slit in PA 85 $^{◦}$. The flux scale is arbitrary. The solid curve illustrates the velocity of the stellar component as derived from all the stellar features present in the spectra. East is to the right and the zero point of the abscissa corresponds to the maximum of the continuum (Fig. 5), and the NaD absorption line flux values have been inverted for presentation purposes. We have derived velocity uncertainties of the order of 10 km s − $^{1}$. Our Model 1 has the following features: tween different components. We will illustrate this for our spectrum of NGC 1358. 4. MODELS a) A stellar bulge with a mass distribution corre- sponding to the continuum surface intensity distri- bution, giving the gravitational field in the nuclear region. As seen in Fig. 5 the observed surface inten- sity distribution can be well represented by the sum of two exponential disks with scale lengths of 0 . $^{′′}$7 and 4 ′′ respectively and an intensity ratio of 4:1, smoothed with the observed PSF. To derive a likely potential and rotation curve for this stellar bulge we use the relation (2–170) of Binney & Tremaine (1987) to give the potential of the sum of two expo- nential spheres with scale lengths 0 . $^{′′}$7 and 4 . $^{′′}$0 re- spectively, and a mass ratio of 4:1 in conformance We will test velocity and intensity observations over the nuclear region against a scenario where the dip in the rotation curve is caused by an outflow of excited gas from a central source at rest with respect to a nuclear gaseous disk. We strive to have in this model an absolute minimum of free parameters to fit the observations. We will first demonstrate the simplest primitive model, here called Model 1, to motivate why we introduce our more elaborate models. 4.1. Model 1