How to Measure the Velocity of a Star

In order to explain the velocity of star s, we have to distribute the mass in just the right way. We can tell how it's distributed by looking at the velocity of stars that are close t centre, and then a little further away,. A distributed mass of dark matter makes a very different prediction than dark matter concentrated all at the core of the galaxy. But remember that we don't know what dark matter is. So it could just be a bunch of black holes spread out through the galaxyw That sounds a little horrifyingo then like if you were flying through space, it's like riddled with minds, kind of riht.