 formula_10 is the semi-major axis (orbital separation) of the binary system.We start out with Kepler's third law, with formula_11 the orbital frequency and formula_12 the gravitational constant,

formula_13

Using the definition of the center of mass location, formula_14, we can write

formula_15

Inserting this expression for formula_16 into Kepler's third law, we find

formula_17

which can be rewritten to

formula_18

The peak radial velocity of object 1, formula_1, depends on the orbital inclination formula_20 (an inclination of 0° corresponds to an orbit seen face-on, an inclination of 90° corresponds to an orbit seen edge-on).For a circular orbit (orbital eccentricity = 0) it is given by

formula_21

After substituting formula_8 we obtain

formula_23

The binary mass function formula_24 (with unit of mass) is

formula_25

For an estimated or assumed mass formula_3 of the observed object 1, a minimum mass formula_27 can be determined for the unseen object 2 by assuming formula_28.