The X-ray binary GX 339-4/V821 Ara: the distance, inclination, evolutionary status and mass transfer

We consider constraints on the distance, inclination and component masses in the X-ray binary GX 339--4 resulting from published works, and then construct detailed evolutionary models for the donor. From both considerations, we find that unless the compact object mass is $approx{3}rm{M}_{odot}$, the possible donor mass is $approx$0.5--$1.4rm{M}_{odot}$, the inclination is $approx{40}^circ$--$60^circ$ and the distance is $approx$8--12 kpc. The corresponding mass of the compact object is $approx$4--$11rm{M}_{odot}$. We then confirm a previous estimate that the theoretical conservative mass transfer rate in GX 339--4 is $lesssim{10^{-9}}rm{M}_{odot}$ yr$^{-1}$. This is $gtrsim$10 times lower than the average mass accretion rate estimated from the long-term X-ray light curve. We show that this discrepancy can be solved in two ways. One solution invokes irradiation of the donor by X-rays from accretion, which can temporarily enhance the mass transfer rate. We found that absorption of a $sim$1 per cent of the irradiating luminosity results in the transfer rate equal to the accretion rate. The time scale at which the transfer rate will vary is estimated to be $sim$10,yr, which appears to be observed. The other solution invokes non-conservative mass transfer. This requires that $approx$70 per cent of the transferred mass escapes as a strong outflow and carries away the specific angular momentum comparable to that of the donor. The time scale of the period increase due to the mass transfer is $approx(3$--$5)times{10^7}$ yr.