ИСТИНА

The observed photometric and spectral variability of CQ Tau implies that circumstellar dust clouds cover the stellar disc inhomogeneously, or in other words, that a typical scale of inhomogeneities in the clouds is comparable to the stellar radius. Сonsequently, the observed extinction law seems more grey than the intrinsic one. Therefore all conclusions about the size distribution of the dust grains in the circumstellar environment of the UX Ori type stars derived from the optical photometry are controversal. Inhomogeneous obscuration of the rotating stellar surface produces features in the line profiles, which give an opportunity to study distribution of the dust absorption over the stellar disc at each moment of observation, i.e. to see the clouds along with their movements.