been proposed (Davidson 1997; Smith et al. 2004; Dorland 2007; Henley et al. 2008; Okazaki et al. 2008).

In a recent paper Kashi & Soker (2008; hereafter KS08) examined a variety of observations that shed light on the orientation of the semi-major axis: (1) The Doppler shifts of some He I P-Cygni lines that are attributed to the secondary wind, of one Fe II line that is attributed to the primary wind, and of the Paschen emission lines that are attributed to the shocked primary wind. (2) The hydrogen column density toward the binary system as deduced from X-ray observations by Hamaguchi et al. (2007; hereafter H07). (3) The ionization of surrounding gas blobs by the radiation of the hotter secondary star. KS08 found that all of these support an orientation where for most of the time the secondary$-$the hotter less massive star$-$is behind the primary star ($\omega=90^\circ$). The secondary comes closer to the observer only for a short time near periastron passage.

In a more recent paper, Parkin et al. (2009, hereafter P09) built a model to fit the X-ray cyclical light curve in the $2-10 \keV$ band as observed by RXTE (Corcoran 2005). From their modelling they deduced 