Photoelectric UBV photometry of the peculiar T Tauri star V1331 Cygni.

The V-band variability range ascertained for V1331 Cyg on the basis of photometry for the 1976-1983 period is 11.70-12.50 mag. This star possesses an emission line spectrum that is characteristic of T Tauri stars, with the additional peculiarity of lines that often show P Cygni profiles. This suggests an intensive outflow of material. Further evidence of mass loss, and the presence of an expanding gaseous envelope, is provided by the blueshifted absorption lines of neutral and singly ionized metals. Its U-B, B-V colors approximately correspond to the continuum of a G0 V star.