SIMBAD references

We address the problem where the X-ray emission lines are formed and investigate orbital dynamics using Chandra HETG observations, photoionizing calculations and numerical wind-particle simulations. The aims were to set constraints on the masses of the components of this close binary system consisting of a Wolf-Rayet (WR) star and a compact component and to investigate the nature of the latter (neutron star or black hole). The goal was also to investigate P Cygni signatures in line profiles. The observed SiXIV (6.185Å) and SXVI (4.733Å) line profiles at four orbital phases were fitted with P Cygni-type profiles consisting of an emission and a blue-shifted absorption component. Numerical models were constructed using photoionizing calculations and particle simulations. In the models, the emission originates in the photoionized wind of the WR companion illuminated by a hybrid source: the X-ray radiation of the compact star and the photospheric EUV-radiation from the WR star. Spectral lines with moderate excitation (such as SiXIV and SXVI) arise in the photoionized wind. The emission component exhibits maximum blue-shift at phase 0.5 (when the compact star is in front), while the velocity of the absorption component is constant (around -900km/s). Both components, like the continuum flux, have intensity maxima around phase 0.5. The simulated FeXXVI Lyα line (1.78Å, H-like) from the wind is weak compared to the observed one. We suggest that it originates in the vicinity of the compact star, with a maximum blue shift at phase 0.25 (compact star approaching). By combining the mass function derived with that from the infrared HeI absorption (arising from the WR companion), we constrain the masses and the inclination of the system. The SiXIV and SXVI lines and their radial velocity curves can be understood in the framework of a photoionized wind involving a hybrid ionizer. Constraints on the compact star mass and orbital inclination (i) are given using the mass functions derived from the FeXXVI line and HeI 2.06µm absorption. Both a neutron star at large inclination (i≥60 degrees) and a black hole at small inclination are possible solutions. The radial velocity amplitude of the HeII 2.09µm emission (formed in the X-ray shadow behind the WR star) suggests i=30 degrees, implying a possible compact star mass between 2.8-8.0M_☉. For i=60 degrees the same range is 1.0-3.2M_☉.