We show that TeV γ-ray emission produced via interactions of high-energy particles with the anisotropic radiation field of a massive star in binary systems should have a characteristic rotating hollow cone anisotropy pattern. The hollow cone, whose axis is directed away from the massive star, rotates with a period equal to the orbital period of the system. We note that the two-maxima pattern of the TeV energy band light curve of the γ-ray-loud binary LS 5039 can be interpreted in terms of this rotating hollow cone model. Adopting such an interpretation, we are able to constrain the geometry of the system-either the inclination angle of the binary orbit, or the elevation of the γ-ray emission region above the orbital plane.
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