Long-term photometric variations in DH Leonis

The long-term photometric behaviour of the triple system DH Leonis has been studied using the UBV data obtained between 1976 and 1990. The amplitude of the long-term brightness change is about 0.45 magnitudes in V, with an estimated cycle length of 8 to 14 years, whereas the amplitude of the rotational modulation is about 0.15 magnitudes. In terms of starspots this means that the variation of spot coverage with longitude (and latitude) at a given time is less than the variation for the whole star over longer intervals of time. During minimum light the effective spotted area covers about 60% of the surface. The average B−V colour of the system is correlated with the average brightness; the change in B−V corresponds to a change of about two spectral subtypes