BH Vir is a short-period eclipsing binary ( P= 0.81687 days, , ) with complicated variations in light curves. Abt (1965) published radial velocity observations from which the mass ratio of the two components was found to be q= m2/m1=1.02. Zhai et al. (1990) re-analyzed the radial velocity curves by Abt (1965) and determined . The first photoelectric observations of BH Vir were obtained 1953 by Kitamura et al. (1957). Koch (1967) noted the remarkable intrinsic variations of BH Vir both outside of and within the eclipses. Hoffmann (1982) concluded that the intrinsic variations arose from both components and suggested that BH Vir should join the short-period RS CVn group. Scaltriti et al. (1985) attributed the activity to the primary star. They used their 1984 observations to obtain a value for , the temperature difference of the cool spotted region relative to the photosphere, of 1300-1400 K.
Budding & Zeilik (1987) analyzed photometric observations made by Sadik (1978) and Scaltriti et al. (1985), and found that the cool spotted regions tend to occur at high latitudes (near 45).
Zeilik et al. (1990) collected completed light curves of BH Vir from 1953 to 1986. They fitted every light curve by a dark, circular spot model for the active regions on the primary star. Their results were K, latitudes near 45, longitudes near 90 and 270.
Zhai et al. (1990) analyzed photoelectric observations by Koch (1967, observations done in 1963-64 in UBV bands) and by Hoffmann (1982, observations done in 1977 in the B and 5125 Å bands) with the Wilson-Devinney program by using a model with two circular dark spots. However they did not consider any activity regions on the secondary star.
The variations of the light curve of BH Vir are rather complicated and certainly prevent precise determinations from photometry analysis. In order to better understand the causes of these distortions, we selected this system in our program and made photoelectric observations.
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