1996A&A...315..400P

On the basis of more than 2300 new Stroemgren y and Johnson V photometric observations collected during 246 hours spread over 42 nights at three sites in 1993, we present a frequency analysis of the light variation of θ Tuc. 10 frequencies were found in the range of 15.8 to 20.28cycles/day displaying an extreme regularity. Frequencies are situated in groups and these groups are equally spaced. Some kind of splitting is definitely involved. The frequencies are constant in amplitude on a short time scale. Two frequencies, 0.282 and 0.142cycles/day (3.56 and 7.04days period) were found to be responsible for the mean light level variation of θ Tuc. Although θ Tuc is known as a single star, the length and shape of the mean light level variation and the unusual behaviour of θ Tuc in ultraviolet and infrared suggest that the δ Scuti star θ Tuc is a primary in a binary system with a late F type companion.