Abstract
Spot photometry in theUBV was obtained for the flare star BY Dra during 1985-1991 at the Bulgarian National Astronomical Observatory. Light curves are presented for 1986, 1987, 1988, and 1991. There are significant variations of the amplitudes of the light curves implying changes of the spot distribution. The phases of the light minima are variable, indicating possible latitudinal migration of the spot and differential rotation. Rough estimate of the corresponding latitudinal shear is in the range 3 × 10−11 −5 × 10−10 rad s−1 deg−1. The photometric behaviour of BY Dra since 1960 shows no compeling evidence for existence of stellar cycles. This is in contradiction with previous studies. During 1985-1991 a total of 38.47 hours of monitoring in theU-filter were obtained. Analysis of the flare activity of BY Dra shows no significant changes from previous studies.
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Panov, K.P., Ivanova, M.S. Photometry of the spotted flare star by dra during 1985-1991. Astrophys Space Sci 199, 265–278 (1993). https://doi.org/10.1007/BF00613200
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DOI: https://doi.org/10.1007/BF00613200