23
Masses
of Binary stars
From our text: Horizons, by Seeds
An example.
Suppose we measured the period in a spectroscopic binary and knew the spectral types (and hence the masses, as we
shall see) of the component
stars. The period is 2 years (P =
2 years) and the stars are a G star (1
solar mass) and a M star (0.5 solar masses). What is the separation?
MA+MB = 1.5 MSun
1.5 x (2)2 = (a/1 AU)3
6 = (a/1 AU)3
1.8
AU = a