The analysis of a homogeneous set of photometric UBV data of the flare star BY Drac for the time interval between 1974 and 1980 indicates that BY Drac exhibits intervals of periodic light variations with amplitudes up to 0.1 magnitude and period of 3d.8285. The duration of these active periods is suggested to be of the order of one or two months and are separated by calm periods. The photometrically active periods coincide either with periods of relatively high flare activity or with periods during which Ha emission is present in the spectrum either of the primary or of the secondary. The phasing of the light minima are in good agreement with the phasing of the flare frequency for the period of relatively high flare activity, ie July 1974. These results are in favour of a starspot modulated light variation model of the star which rotates with a period of 3d.8285. The starspot lifetime should be comparable to that of the sunspot and the longitudinal location of the starspot area should be mobil.
Joint European and National Astronomical Meeting
- Pub Date: