SIMBAD references

We model the emission-line profile variations that are expected to be produced by physical and wind eclipses in the Wolf-Rayet (W-R+O) binary system V444 Cyg. A comparison of the theoretical profiles with the He II 4686 Å line observed in V444 Cyg allows us to isolate the effects that are likely to be due to the wind-wind collision region in this particular line. We estimate that the wind-wind collision region contributes no more than ∼12% of the equivalent width of the emission line, with smaller values during elongations, when part of the shock cone is being eclipsed by the O star. The upper limit implies a maximum contribution from the wind-wind collision region of ∼1x10³⁵ ergs.s^–1 to the total luminosity of He II 4686 Å line. Using the analytical solution of Cantó et al., we find that the bulk of this emission arises along the shock cone walls where the flow velocity is ∼800 km.s^–1, at a distance of ∼8 R_☉ from the O star's surface, and at θ=65°-75° from the line joining the centers of the two stars, with origin in the O star. The derived surface density of this region is σ=0.22 g.cm^–2, which, together with the He II 4686 Å luminosity, indicates that the thickness of the shock lies in the range 2-10x10¹⁰ cm and the total density is 1-6x10¹² cm^–3.