VRI LIGHT CURVES OF SS-433 - PHOTOMETRY AND MODEL

We present the results of VRI CCD photometric observations of SS 433 a nd VRI light-curve modelings for SS 433. Observations were carried out in the fall of 1995 using the 51-cm relfector at Osaka Kyoiku Univers ity. Three cycles of the binary phase were covered. The mean magnitude s and colors during the observational periods were V = 14.0, R = 11.1, I = 10.5; V - R = 2.88, V - I = 3.50, R - I = 0.62. On October 17 and 18 a strong flare was observed. Theoretical light curves were also ca lculated using a model in which SS 433 consists of a geometrically thi ck torus around a compact star and a companion star filling the Roche lobe. In the torus picture VRI light curves were first calculated; for appropriate parameters VRI model light curves well reproduce the obse rvational profiles. In addition, the extinction was first derived from the magnitude difference between the obervation and the model; A(V) s imilar to 6-7, A(R) similar to 3-4, and A(I) similar to 3. These value s are in good agreement with those of a previous observation.