Star velocity can be measured using the absorption line spectrum, and comparing it to the spectrum of a single star in our own galaxy. The offset gives the redshift, while the difference in widths gives the velocity dispersion. There are several methods for performing these measurements (see Topic 7 sec 6a)
Observations of the (projected) velocity of the gas (open circles) and the stars (filled circles) along the major axis of NGC 7184. In the disk, the stars and gas are both close to full rotational support, with Vrot = Vc. The stars may have slightly lower rotation amplitude, consistent with a small amount of dispersion support.