U-PHOTOMETRY, J-PHOTOMETRY, K-PHOTOMETRY OF V444-CYG - THE STRUCTURE OF THE EXTENDED ATMOSPHERE OF THE WN5 STAR

Coordinated, quasi simultaneous photoelectric observations of the ecli psing system V444 Cyg (WN5 + O6) in the filters U,J,K were carried out in order to determine the dependence of atmospheric parameters of the WN5 star on the wave length. It was confirmed that the size of the lu minous extended atmosphere of the WN5 star greatly increases with incr easing wave length, evidencing for clumpy structure of the stellar win d from the WN5 star. However, infrared light curves around the princip al minimum differ considerably from those obtained by Hartmann 10 year s earlier, causing difficulties both for homogeneous and for clumpy mo dels of the WR star wind. It is possible that the variability of infra red light curves of V444 Cyg is due to changes of the physical structu re of the wind from the WN5 star.