What property is measured using the Doppler shift of emitted light or radio waves from orbiting objects?

Answer

Orbital velocity of stars/gas clouds.

The Doppler shift reveals whether an object is moving toward (blueshift) or away (redshift), which allows astronomers to measure its orbital velocity ($v$).

What property is measured using the Doppler shift of emitted light or radio waves from orbiting objects?
physicsmeasurementgalaxyastronomymass