center of
mass.
r1
r2
m1
m2
for the physicist, let a = r1 +
r2 and P = period of binary orbit, then
Fgrav = G m1m2/ a2
= m1 v12/r1
= m1 4p2r1/P2
r1/r2 = m2/m1 , then r1 =m2a/(m1+m2)
Ž P2 = a34p2/(G(m1+m2)) (Kepler’s 3rd
law)
get m1+m2 from P, a and 3rd law
get m1/m2 from r1/r2 = m2/m1 ]
Estimating
stellar masses
Gravitational effect on
another body ® mass
stellar mass from binary stars
BUT unknown inclination of
orbit to line of sight can
limit
information