SIMBAD references

We constructed a DF Tau historical lightcurve to analyze the character of stellar variability from 1900 to 2000. This time interval exceeds the orbital period P≃80yrs of the double system. At least two sections of enhanced photometric activity are present in the lightcurve, with the time interval between them being close to P/2. They correspond to the sections of the DF Tau companion orbit intermediate between apo- and periastron. A decrease in stellar activity occured near the last periastron epoch. We conclude that long-term variations of DF Tau activity are the result of modulation of primary circumstellar disc accretion rate by orbital motion of the companion. We predict that DF Tau activity will increase significantly in the near future.