1. The problem statement, all variables and given/known data We observe a binary system in which the two stars are 1 and 2 arc sec, respectively, from the center of mass. The system is 10pc from us. The period is 33 yr. What are the masses of the two stars, assuming that i=90 degrees? 2. Relevant equations 3. The attempt at a solution I want to derive an equation for the masses based on what we know, so here goes. Based on a simple sketch of the system, we know mara = mbrb. We can label the distance between the two stars r = ra + rb re-arranging and substituting yields mara = mb(r-ra) Then ra = mbr/ma + mb = mbr/M where M = ma + mb Now, force of Gravity must equal centripetal force in this binary system, so Gmamb/r2 = mava2/ra since v = d/t, va = 2[tex]\pi[/tex]ra/T where T is the period. re-arranging once again yields ra = GmbT2/4r2[tex]\pi[/tex]2 subbing in from our equation for ra yields M = 4r3[tex]\pi[/tex]2/GT2 Now we have an equation for the total mass of the system, but I need individual masses. Can anyone confirm my equation? Am I on the right track? Where does the inclination of the system come in? Is it just for an assumption? Likewise, where does the system distance d away from us come into play? Am I missing something here? Any help would be appreciated thanks.