Complex behaviour of the δ Scuti star θ Tucanae. I. Frequencies in the light variation.
Abstract
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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1996
- Bibcode:
- 1996A&A...315..400P
- Keywords:
-
- STARS: INDIVIDUAL: {THETA} TUC = HR 139;
- STARS: OSCILLATIONS;
- STARS: VARIABLES: {DELTA} SCUTI;
- INFRARED: STARS;
- ULTRAVIOLET: STARS;
- STARS: BINARIES: GENERAL