Interpretation of the light curve of the eclipsing binary V444 Cyg on the set of convexo-concave functions

The narrow-band λ4244 Å continuum light curve of the eclipsing binary V444 Cyg, which has a Wolf-Rayet component, is interpreted assuming that the brightness distribution and absorption in the WN5 star's disk are monotonic, non-increasing, convexo-concave, non-negative functions. The convex and concave parts of these functions correspond to the core of the WN5 star and its extended photosphere and atmosphere, respectively. The radius and brightness temperature of the opaque core of the WN5 star are r _WN5 ^core ? 4R _⊙ and T _br ^core >52000 K, respectively. The stellar wind is characterized by an accelerated radial outflow. Acceleration of the wind persists at large distances from the center of the star. A crude Lamers-law fit to the reconstructed velocity field in the wind yields an acceleration parameter β=1.58–1.82.