On the masses and evolutionary status of the black hole binary GX 339-4: a twin system of XTE J1550-564?

We apply the K-correction to the black hole low-mass X-ray binary (LMXB) GX 339-4 which implies MX≥ 6 M⊙ by only assuming that the companion is more massive than ∼0.17 M⊙, the lower limit allowed by applying a ‘stripped-giant’ model. This evolutionary model successfully reproduces the observed properties of the system. We obtain a maximum mass for the companion of M2≤ 1.1 M⊙ and an upper limit to the mass ratio of q(=M2/MX) ≤ 0.125. The high X-ray activity displayed by the source suggests a relatively large mass transfer rate which, according to the model, results in M2≳ 0.3 M⊙ and MX≳ 7 M⊙. We have also applied this scenario to the black hole binary XTE J1550-564, which has a similar orbital period but the donor is detected spectroscopically. The model successfully reproduces the observed stellar parameters.