The X-ray photoionized wind in Cen X-3/V779 Cen

We analyze the ASCA spectrum of the Cen X-3 X-ray binary system in eclipse using atomic models appropriate to recombination-dominated level population kinetics in an overionized plasma. In order to estimate the wind character istics, we first fit the eclipse spectrum to a single-zone photoionized pla sma model. We then fit spectra from a range of orbital phases using global models of photoionized winds from the companion star and the accretion disk that account for the continuous distribution of density and ionization sta te. We find that the spectrum can be reproduced by a density distribution o f the form derived by Castor et al. (1975) for radiation-driven winds with (M) over dot/v(infinity) consistent with values for isolated stars of the s ame stellar type. This is surprising because the neutron star is very lumin ous (similar to 10(38) ergs s(-1)) and the X-rays from the neutron star sho uld ionize the wind and destroy the ions that provide the opacity for the r adiation-driven wind. Using the same functional form for the density profil e, we also fit the spectrum to a spherically symmetric wind centered on the neutron star, a configuration chosen to represent a disk wind. We argue th at the relatively modest orbital variation of the discrete spectrum rules o ut a disk wind hypothesis.