Using the two numeric input boxes beside the radio button you will find that you can manipulate the density of the disc and also its extent.
You will soon discover that you can produce a hump in the rotation curve but there is no way you can match all the data points.
See if you can produce a better match using one of the other distributions.
If you want to generate your own density distribution curve, select the 'Custom' option and use the LEFT hand button on the mouse to adjust the curve directly.
Recent studies (eg Korchagin 2003) have measured the local surface density of visible matter in the region of our Sun quite accurately and it turns out to be about 42 ± 6 MO pc-2. This translates (see note below) into a volume density on our scale of (2.8 ± 0.5) x 10-21 kg m-3. This point is marked on the graph and to be consistent with this data, your density distribution curve must pass through it.
Measurement of the vertical velocities of stars above and below the disc largely confirm this figure showing that there is little, if any dark matter withing the disc itself.
Note that for the purposes of this program and for consistency, the densities of both halo and disc are expressed in units of 10-21 kg m-3 and the disc is assumed to have a uniform thickness of 1000 pc. The surface density of the disc can therefore be calculated by multiplying the Y scale by 15.