The size of the shift (Redshift or Blue shift) combined with measurement of the period of orbit tells us how massive an object is. How? How can we know the mass of a planet using redshift or blue shift?
Calculating the force is an unnecessary detour if you are interested in the mass, but it is possible.What if we use the formula F=ma or m=F/a to figure out the mass of this planet? If we observe the wobble can we estimate the gravitational force F? Also if me observe the orbit speed we could get to know the acceleration?