content_image/421089.jpg
<img src='content_image/421089.jpg'>

tween different components. We will illustrate this for our spectrum of NGC 1358. 

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. MODELS 

## 4.1. Model 1 

Our Model 1 has the following features: 

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 

