  We consider the propagation of very high energy (VHE) gamma-rays in the
radiation field of the massive star of binary system Cen X-3. VHE gamma-rays or
electrons, injected by the compact object close to the surface of a massive
companion, develop inverse Compton pair (ICS) cascades. Based on the Monte
Carlo simulations, we obtain the fraction of secondary cascade photons which
collide with the surface of the massive companion in Cen X-3 system. The
distribution of photons falling on the surface of the massive star is
investigated. These photons interact with the atmosphere of the star and should
excite different gamma-ray lines (nuclear, electron-positron annihilation
line). We estimate that these gamma-ray lines can be likely detected by the
INTEGRAL telescopes.

Astrophysics