The spectral lines of two stars in a particular eclipsing binary system shift back and forth with a period of 9 months. The lines of both stars shift by equal amounts, and the amount of the Doppler shift indicates that each star has an orbital speed of 9.0×104 m/s
relative to the other.
What are the masses of the two stars? Assume that each of the two stars traces a circular orbit around their center of mass. (Hint: See Mathematical Insight Measuring Stellar Masses.)
Express your answer using two significant figures.
I have tried to use the formula m1+m2=a^3/p^2 for binary systems but it doesn't seem to work and I get and extremely small value (82) which is definetly incorrect.