the hard X-ray is the post-shocked secondary wind (Pittard & Corcoran 2002; Corcoran 2005; A06), taken here at the point marked on Fig. \[fig:NHgeo\] by ‘X-ray source’. This point is located at a distance of $(1-u)D_{g2}$ from the stagnation point, or a distance of $uD_{g2}$ from that point. The X-ray emitting region is more extended, but it does not extend to large distances from the secondary, and our assumption is adequate. We assume $u = 0.7$. As evident from the figure, the column density has two main components: The post-shocked primary wind component, $N_{H,\rm{shock}}$ (the conical shell), and the undisturbed, free-expanding, primary wind component ($N_{Hi1}$). We calculate the contribution of each component to the total column density ($N_{H,\rm{tot}}$) as a function of orbital angle $\theta$ ($\theta$=0 at periastron).

As in our previous papers, we approximate the shape of the colliding winds conical shell as an hyperploid. In the present study we consider some additional effects, listed next, that makes the geometry more complicated and the results more accurate. Similar considerations were used by us (Kashi & Soker 2009b) to explain the complex P Cygni profile of the He I $\lambda 10830$[Å]{} high excitation line.

\(1) **Wind acceleration.** We take the 