SIMBAD references

We report the evidence of the orbital motion of the binary star DF Tau. This result is obtained from visible speckle interferometry and uses lunar occultations of Chen et al. (1990). It is the first step towards a direct determination of the dynamical mass of this young system. The portion of the orbit covered between the epochs of observation is still too small (∼10%) to allow precise derivation of the orbital elements. We however provide a first estimate of the mass of the system as being 2.8±1.5M_sun. We investigate the incidence of the binarity of DF Tau on the modeling of its spectral energy distribution and discuss the nature of the components.